forked from lijiext/lammps
1807 lines
77 KiB
Plaintext
1807 lines
77 KiB
Plaintext
"Previous Section"_Section_intro.html - "LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc - "Next Section"_Section_commands.html :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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2. Getting Started :h3
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This section describes how to build and run LAMMPS, for both new and
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experienced users.
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2.1 "What's in the LAMMPS distribution"_#start_1
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2.2 "Making LAMMPS"_#start_2
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2.3 "Making LAMMPS with optional packages"_#start_3
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2.4 "Building LAMMPS via the Make.py script"_#start_4
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2.5 "Building LAMMPS as a library"_#start_5
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2.6 "Running LAMMPS"_#start_6
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2.7 "Command-line options"_#start_7
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2.8 "Screen output"_#start_8
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2.9 "Tips for users of previous versions"_#start_9 :all(b)
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:line
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:line
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2.1 What's in the LAMMPS distribution :h4,link(start_1)
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When you download a LAMMPS tarball you will need to unzip and untar
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the downloaded file with the following commands, after placing the
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tarball in an appropriate directory.
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gunzip lammps*.tar.gz
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tar xvf lammps*.tar :pre
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This will create a LAMMPS directory containing two files and several
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sub-directories:
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README: text file
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LICENSE: the GNU General Public License (GPL)
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bench: benchmark problems
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doc: documentation
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examples: simple test problems
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potentials: embedded atom method (EAM) potential files
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src: source files
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tools: pre- and post-processing tools :tb(s=:)
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Note that the "download page"_download also has links to download
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Windows exectubles and installers, as well as pre-built executables
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for a few specific Linux distributions. It also has instructions for
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how to download/install LAMMPS for Macs (via Homebrew), and to
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download and update LAMMPS from SVN and Git repositories, which gives
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you the same files that are in the download tarball.
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The Windows and Linux executables for serial or parallel only include
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certain packages and bug-fixes/upgrades listed on "this
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page"_http://lammps.sandia.gov/bug.html up to a certain date, as
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stated on the download page. If you want an executable with
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non-included packages or that is more current, then you'll need to
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build LAMMPS yourself, as discussed in the next section.
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Skip to the "Running LAMMPS"_#start_6 sections for info on how to
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launch a LAMMPS Windows executable on a Windows box.
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:line
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2.2 Making LAMMPS :h4,link(start_2)
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This section has the following sub-sections:
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"Read this first"_#start_2_1
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"Steps to build a LAMMPS executable"_#start_2_2
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"Common errors that can occur when making LAMMPS"_#start_2_3
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"Additional build tips"_#start_2_4
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"Building for a Mac"_#start_2_5
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"Building for Windows"_#start_2_6 :ul
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:line
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[{Read this first:}] :link(start_2_1)
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If you want to avoid building LAMMPS yourself, read the preceeding
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section about options available for downloading and installing
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executables. Details are discussed on the "download"_download page.
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Building LAMMPS can be simple or not-so-simple. If all you need are
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the default packages installed in LAMMPS, and MPI is already installed
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on your machine, or you just want to run LAMMPS in serial, then you
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can typically use the Makefile.mpi or Makefile.serial files in
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src/MAKE and type one of these lines (from the src dir):
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make mpi
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make serial :pre
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Or if one of the other Makefile.machine files in the src/MAKE
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sub-directories matches your system (type "make" to see a list), you
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can use it as-is by typing (for example):
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make stampede :pre
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If any of these builds with an existing Makefile.machine works on your
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system, then you're done!
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If you want to do one of these:
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use optional LAMMPS features that require additional libraries
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use optional packages that require additional libraries
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use optional accelerator packages that require special compiler/linker settings
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run on a specialized platform like a supercomputer that has its own compilers, settings, or other libs to use :ul
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then building LAMMPS is more complicated. You may need to find where
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auxiliary libraries exist on your machine or install them if they
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don't. You may need to build additional libraries that are part of
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the LAMMPS package, before building LAMMPS. You may need to edit a
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Makefile.machine file to make it compatible with your system.
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Note that there is a Make.py tool in the src directory that automates
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several of these steps, but you still have to know what you are doing.
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"Section 2.4"_#start_4 below describes the tool. It is a convenient
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way to work with installing/un-installing various packages, the
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Makefile.machine changes required by some packages, and the auxiliary
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libraries some of them use.
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Please read the following sections carefully. If you are not
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comfortable with makefiles, or building codes on a Unix platform, or
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running an MPI job on your machine, please find a local expert to help
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you. Many compilation, linking, and run problems that users have are
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often not really LAMMPS issues - they are peculiar to the user's
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system, compilers, libraries, etc. Such questions are better answered
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by a local expert.
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If you have a build problem that you are convinced is a LAMMPS issue
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(e.g. the compiler complains about a line of LAMMPS source code), then
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please post the issue to the "LAMMPS mail
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list"_http://lammps.sandia.gov/mail.html.
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If you succeed in building LAMMPS on a new kind of machine, for which
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there isn't a similar machine Makefile included in the src/MAKE/MORE
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directory, then send it to the developers and we can include it in the
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LAMMPS distribution.
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:line
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[{Steps to build a LAMMPS executable:}] :link(start_2_2)
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[Step 0]
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The src directory contains the C++ source and header files for LAMMPS.
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It also contains a top-level Makefile and a MAKE sub-directory with
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low-level Makefile.* files for many systems and machines. See the
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src/MAKE/README file for a quick overview of what files are available
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and what sub-directories they are in.
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The src/MAKE dir has a few files that should work as-is on many
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platforms. The src/MAKE/OPTIONS dir has more that inovke additional
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compiler, MPI, and other setting options commonly used by LAMMPS, to
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illustrate their syntax. The src/MAKE/MACHINES dir has many more that
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have been tweaked or optimized for specific machines. These files are
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all good starting points if you find you need to change them for your
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machine. Put any file you edit into the src/MAKE/MINE directory and
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it will be never be touched by any LAMMPS updates.
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From within the src directory, type "make" or "gmake". You should see
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a list of available choices from src/MAKE and all of its
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sub-directories. If one of those has the options you want or is the
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machine you want, you can type a command like:
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make mpi
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or
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make serial_icc
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or
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gmake mac :pre
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Note that the corresponding Makefile.machine can exist in src/MAKE or
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any of its sub-directories. If a file with the same name appears in
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multiple places (not a good idea), the order they are used is as
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follows: src/MAKE/MINE, src/MAKE, src/MAKE/OPTIONS, src/MAKE/MACHINES.
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This gives preference to a file you have created/edited and put in
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src/MAKE/MINE.
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Note that on a multi-processor or multi-core platform you can launch a
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parallel make, by using the "-j" switch with the make command, which
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will build LAMMPS more quickly.
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If you get no errors and an executable like lmp_mpi or lmp_g++_serial
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or lmp_mac is produced, then you're done; it's your lucky day.
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Note that by default only a few of LAMMPS optional packages are
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installed. To build LAMMPS with optional packages, see "this
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section"_#start_3 below.
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[Step 1]
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If Step 0 did not work, you will need to create a low-level Makefile
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for your machine, like Makefile.foo. You should make a copy of an
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existing Makefile.* in src/MAKE or one of its sub-directories as a
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starting point. The only portions of the file you need to edit are
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the first line, the "compiler/linker settings" section, and the
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"LAMMPS-specific settings" section. When it works, put the edited
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file in src/MAKE/MINE and it will not be altered by any future LAMMPS
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updates.
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[Step 2]
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Change the first line of Makefile.foo to list the word "foo" after the
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"#", and whatever other options it will set. This is the line you
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will see if you just type "make".
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[Step 3]
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The "compiler/linker settings" section lists compiler and linker
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settings for your C++ compiler, including optimization flags. You can
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use g++, the open-source GNU compiler, which is available on all Unix
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systems. You can also use mpicxx which will typically be available if
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MPI is installed on your system, though you should check which actual
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compiler it wraps. Vendor compilers often produce faster code. On
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boxes with Intel CPUs, we suggest using the Intel icc compiler, which
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can be downloaded from "Intel's compiler site"_intel.
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:link(intel,http://www.intel.com/software/products/noncom)
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If building a C++ code on your machine requires additional libraries,
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then you should list them as part of the LIB variable. You should
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not need to do this if you use mpicxx.
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The DEPFLAGS setting is what triggers the C++ compiler to create a
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dependency list for a source file. This speeds re-compilation when
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source (*.cpp) or header (*.h) files are edited. Some compilers do
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not support dependency file creation, or may use a different switch
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than -D. GNU g++ and Intel icc works with -D. If your compiler can't
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create dependency files, then you'll need to create a Makefile.foo
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patterned after Makefile.storm, which uses different rules that do not
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involve dependency files. Note that when you build LAMMPS for the
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first time on a new platform, a long list of *.d files will be printed
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out rapidly. This is not an error; it is the Makefile doing its
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normal creation of dependencies.
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[Step 4]
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The "system-specific settings" section has several parts. Note that
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if you change any -D setting in this section, you should do a full
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re-compile, after typing "make clean" (which will describe different
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clean options).
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The LMP_INC variable is used to include options that turn on ifdefs
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within the LAMMPS code. The options that are currently recogized are:
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-DLAMMPS_GZIP
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-DLAMMPS_JPEG
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-DLAMMPS_PNG
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-DLAMMPS_FFMPEG
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-DLAMMPS_MEMALIGN
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-DLAMMPS_XDR
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-DLAMMPS_SMALLBIG
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-DLAMMPS_BIGBIG
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-DLAMMPS_SMALLSMALL
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-DLAMMPS_LONGLONG_TO_LONG
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-DPACK_ARRAY
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-DPACK_POINTER
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-DPACK_MEMCPY :ul
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The read_data and dump commands will read/write gzipped files if you
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compile with -DLAMMPS_GZIP. It requires that your machine supports
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the "popen" function in the standard runtime library and that a gzip
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executable can be found by LAMMPS during a run.
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If you use -DLAMMPS_JPEG, the "dump image"_dump_image.html command
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will be able to write out JPEG image files. For JPEG files, you must
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also link LAMMPS with a JPEG library, as described below. If you use
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-DLAMMPS_PNG, the "dump image"_dump.html command will be able to write
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out PNG image files. For PNG files, you must also link LAMMPS with a
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PNG library, as described below. If neither of those two defines are
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used, LAMMPS will only be able to write out uncompressed PPM image
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files.
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If you use -DLAMMPS_FFMPEG, the "dump movie"_dump_image.html command
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will be available to support on-the-fly generation of rendered movies
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the need to store intermediate image files. It requires that your
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machines supports the "popen" function in the standard runtime library
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and that an FFmpeg executable can be found by LAMMPS during the run.
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Using -DLAMMPS_MEMALIGN=<bytes> enables the use of the
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posix_memalign() call instead of malloc() when large chunks or memory
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are allocated by LAMMPS. This can help to make more efficient use of
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vector instructions of modern CPUS, since dynamically allocated memory
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has to be aligned on larger than default byte boundaries (e.g. 16
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bytes instead of 8 bytes on x86 type platforms) for optimal
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performance.
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If you use -DLAMMPS_XDR, the build will include XDR compatibility
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files for doing particle dumps in XTC format. This is only necessary
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if your platform does have its own XDR files available. See the
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Restrictions section of the "dump"_dump.html command for details.
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Use at most one of the -DLAMMPS_SMALLBIG, -DLAMMPS_BIGBIG, -D-
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DLAMMPS_SMALLSMALL settings. The default is -DLAMMPS_SMALLBIG. These
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settings refer to use of 4-byte (small) vs 8-byte (big) integers
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within LAMMPS, as specified in src/lmptype.h. The only reason to use
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the BIGBIG setting is to enable simulation of huge molecular systems
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(which store bond topology info) with more than 2 billion atoms, or to
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track the image flags of moving atoms that wrap around a periodic box
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more than 512 times. The only reason to use the SMALLSMALL setting is
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if your machine does not support 64-bit integers. See the "Additional
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build tips"_#start_2_4 section below for more details.
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The -DLAMMPS_LONGLONG_TO_LONG setting may be needed if your system or
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MPI version does not recognize "long long" data types. In this case a
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"long" data type is likely already 64-bits, in which case this setting
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will convert to that data type.
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Using one of the -DPACK_ARRAY, -DPACK_POINTER, and -DPACK_MEMCPY
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options can make for faster parallel FFTs (in the PPPM solver) on some
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platforms. The -DPACK_ARRAY setting is the default. See the
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"kspace_style"_kspace_style.html command for info about PPPM. See
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Step 6 below for info about building LAMMPS with an FFT library.
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[Step 5]
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The 3 MPI variables are used to specify an MPI library to build LAMMPS
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with. Note that you do not need to set these if you use the MPI
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compiler mpicxx for your CC and LINK setting in the section above.
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The MPI wrapper knows where to find the needed files.
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If you want LAMMPS to run in parallel, you must have an MPI library
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installed on your platform. If MPI is installed on your system in the
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usual place (under /usr/local), you also may not need to specify these
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3 variables, assuming /usr/local is in your path. On some large
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parallel machines which use "modules" for their compile/link
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environements, you may simply need to include the correct module in
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your build environment, before building LAMMPS. Or the parallel
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machine may have a vendor-provided MPI which the compiler has no
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trouble finding.
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Failing this, these 3 variables can be used to specify where the mpi.h
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file (MPI_INC) and the MPI library file (MPI_PATH) are found and the
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name of the library file (MPI_LIB).
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If you are installing MPI yourself, we recommend Argonne's MPICH2
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or OpenMPI. MPICH can be downloaded from the "Argonne MPI
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site"_http://www.mcs.anl.gov/research/projects/mpich2/. OpenMPI can
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be downloaded from the "OpenMPI site"_http://www.open-mpi.org.
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Other MPI packages should also work. If you are running on a big
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parallel platform, your system people or the vendor should have
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already installed a version of MPI, which is likely to be faster
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than a self-installed MPICH or OpenMPI, so find out how to build
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and link with it. If you use MPICH or OpenMPI, you will have to
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configure and build it for your platform. The MPI configure script
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should have compiler options to enable you to use the same compiler
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you are using for the LAMMPS build, which can avoid problems that can
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arise when linking LAMMPS to the MPI library.
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If you just want to run LAMMPS on a single processor, you can use the
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dummy MPI library provided in src/STUBS, since you don't need a true
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MPI library installed on your system. See src/MAKE/Makefile.serial
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for how to specify the 3 MPI variables in this case. You will also
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need to build the STUBS library for your platform before making LAMMPS
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itself. Note that if you are building with src/MAKE/Makefile.serial,
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e.g. by typing "make serial", then the STUBS library is built for you.
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To build the STUBS library from the src directory, type "make stubs",
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or from the src/STUBS dir, type "make". This should create a
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libmpi_stubs.a file suitable for linking to LAMMPS. If the build
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fails, you will need to edit the STUBS/Makefile for your platform.
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The file STUBS/mpi.c provides a CPU timer function called MPI_Wtime()
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that calls gettimeofday() . If your system doesn't support
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gettimeofday() , you'll need to insert code to call another timer.
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Note that the ANSI-standard function clock() rolls over after an hour
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or so, and is therefore insufficient for timing long LAMMPS
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simulations.
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[Step 6]
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The 3 FFT variables allow you to specify an FFT library which LAMMPS
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uses (for performing 1d FFTs) when running the particle-particle
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particle-mesh (PPPM) option for long-range Coulombics via the
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"kspace_style"_kspace_style.html command.
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LAMMPS supports various open-source or vendor-supplied FFT libraries
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for this purpose. If you leave these 3 variables blank, LAMMPS will
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use the open-source "KISS FFT library"_http://kissfft.sf.net, which is
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included in the LAMMPS distribution. This library is portable to all
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platforms and for typical LAMMPS simulations is almost as fast as FFTW
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or vendor optimized libraries. If you are not including the KSPACE
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package in your build, you can also leave the 3 variables blank.
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Otherwise, select which kinds of FFTs to use as part of the FFT_INC
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setting by a switch of the form -DFFT_XXX. Recommended values for XXX
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are: MKL, SCSL, FFTW2, and FFTW3. Legacy options are: INTEL, SGI,
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ACML, and T3E. For backward compatability, using -DFFT_FFTW will use
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the FFTW2 library. Using -DFFT_NONE will use the KISS library
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described above.
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You may also need to set the FFT_INC, FFT_PATH, and FFT_LIB variables,
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so the compiler and linker can find the needed FFT header and library
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files. Note that on some large parallel machines which use "modules"
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for their compile/link environements, you may simply need to include
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the correct module in your build environment. Or the parallel machine
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may have a vendor-provided FFT library which the compiler has no
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trouble finding.
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FFTW is a fast, portable library that should also work on any
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platform. You can download it from
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"www.fftw.org"_http://www.fftw.org. Both the legacy version 2.1.X and
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the newer 3.X versions are supported as -DFFT_FFTW2 or -DFFT_FFTW3.
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Building FFTW for your box should be as simple as ./configure; make.
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Note that on some platforms FFTW2 has been pre-installed, and uses
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renamed files indicating the precision it was compiled with,
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e.g. sfftw.h, or dfftw.h instead of fftw.h. In this case, you can
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specify an additional define variable for FFT_INC called -DFFTW_SIZE,
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which will select the correct include file. In this case, for FFT_LIB
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you must also manually specify the correct library, namely -lsfftw or
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-ldfftw.
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The FFT_INC variable also allows for a -DFFT_SINGLE setting that will
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use single-precision FFTs with PPPM, which can speed-up long-range
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calulations, particularly in parallel or on GPUs. Fourier transform
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and related PPPM operations are somewhat insensitive to floating point
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truncation errors and thus do not always need to be performed in
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double precision. Using the -DFFT_SINGLE setting trades off a little
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accuracy for reduced memory use and parallel communication costs for
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transposing 3d FFT data. Note that single precision FFTs have only
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been tested with the FFTW3, FFTW2, MKL, and KISS FFT options.
|
|
|
|
[Step 7]
|
|
|
|
The 3 JPG variables allow you to specify a JPEG and/or PNG library
|
|
which LAMMPS uses when writing out JPEG or PNG files via the "dump
|
|
image"_dump_image.html command. These can be left blank if you do not
|
|
use the -DLAMMPS_JPEG or -DLAMMPS_PNG switches discussed above in Step
|
|
4, since in that case JPEG/PNG output will be disabled.
|
|
|
|
A standard JPEG library usually goes by the name libjpeg.a or
|
|
libjpeg.so and has an associated header file jpeglib.h. Whichever
|
|
JPEG library you have on your platform, you'll need to set the
|
|
appropriate JPG_INC, JPG_PATH, and JPG_LIB variables, so that the
|
|
compiler and linker can find it.
|
|
|
|
A standard PNG library usually goes by the name libpng.a or libpng.so
|
|
and has an associated header file png.h. Whichever PNG library you
|
|
have on your platform, you'll need to set the appropriate JPG_INC,
|
|
JPG_PATH, and JPG_LIB variables, so that the compiler and linker can
|
|
find it.
|
|
|
|
As before, if these header and library files are in the usual place on
|
|
your machine, you may not need to set these variables.
|
|
|
|
[Step 8]
|
|
|
|
Note that by default only a few of LAMMPS optional packages are
|
|
installed. To build LAMMPS with optional packages, see "this
|
|
section"_#start_3 below, before proceeding to Step 9.
|
|
|
|
[Step 9]
|
|
|
|
That's it. Once you have a correct Makefile.foo, and you have
|
|
pre-built any other needed libraries (e.g. MPI, FFT, etc) all you need
|
|
to do from the src directory is type something like this:
|
|
|
|
make foo
|
|
or
|
|
gmake foo :pre
|
|
|
|
You should get the executable lmp_foo when the build is complete.
|
|
|
|
:line
|
|
|
|
[{Errors that can occur when making LAMMPS:}] :link(start_2_3)
|
|
|
|
IMPORTANT NOTE: If an error occurs when building LAMMPS, the compiler
|
|
or linker will state very explicitly what the problem is. The error
|
|
message should give you a hint as to which of the steps above has
|
|
failed, and what you need to do in order to fix it. Building a code
|
|
with a Makefile is a very logical process. The compiler and linker
|
|
need to find the appropriate files and those files need to be
|
|
compatible with LAMMPS source files. When a make fails, there is
|
|
usually a very simple reason, which you or a local expert will need to
|
|
fix.
|
|
|
|
Here are two non-obvious errors that can occur:
|
|
|
|
(1) If the make command breaks immediately with errors that indicate
|
|
it can't find files with a "*" in their names, this can be because
|
|
your machine's native make doesn't support wildcard expansion in a
|
|
makefile. Try gmake instead of make. If that doesn't work, try using
|
|
a -f switch with your make command to use a pre-generated
|
|
Makefile.list which explicitly lists all the needed files, e.g.
|
|
|
|
make makelist
|
|
make -f Makefile.list linux
|
|
gmake -f Makefile.list mac :pre
|
|
|
|
The first "make" command will create a current Makefile.list with all
|
|
the file names in your src dir. The 2nd "make" command (make or
|
|
gmake) will use it to build LAMMPS. Note that you should
|
|
include/exclude any desired optional packages before using the "make
|
|
makelist" command.
|
|
|
|
(2) If you get an error that says something like 'identifier "atoll"
|
|
is undefined', then your machine does not support "long long"
|
|
integers. Try using the -DLAMMPS_LONGLONG_TO_LONG setting described
|
|
above in Step 4.
|
|
|
|
:line
|
|
|
|
[{Additional build tips:}] :link(start_2_4)
|
|
|
|
(1) Building LAMMPS for multiple platforms.
|
|
|
|
You can make LAMMPS for multiple platforms from the same src
|
|
directory. Each target creates its own object sub-directory called
|
|
Obj_target where it stores the system-specific *.o files.
|
|
|
|
(2) Cleaning up.
|
|
|
|
Typing "make clean-all" or "make clean-machine" will delete *.o object
|
|
files created when LAMMPS is built, for either all builds or for a
|
|
particular machine.
|
|
|
|
(3) Changing the LAMMPS size limits via -DLAMMPS_SMALLBIG or
|
|
-DLAMMPS_BIGBIG or -DLAMMPS_SMALLSMALL
|
|
|
|
As explained above, any of these 3 settings can be specified on the
|
|
LMP_INC line in your low-level src/MAKE/Makefile.foo.
|
|
|
|
The default is -DLAMMPS_SMALLBIG which allows for systems with up to
|
|
2^63 atoms and 2^63 timesteps (about 9e18). The atom limit is for
|
|
atomic systems which do not store bond topology info and thus do not
|
|
require atom IDs. If you use atom IDs for atomic systems (which is
|
|
the default) or if you use a molecular model, which stores bond
|
|
topology info and thus requires atom IDs, the limit is 2^31 atoms
|
|
(about 2 billion). This is because the IDs are stored in 32-bit
|
|
integers.
|
|
|
|
Likewise, with this setting, the 3 image flags for each atom (see the
|
|
"dump"_dump.html doc page for a discussion) are stored in a 32-bit
|
|
integer, which means the atoms can only wrap around a periodic box (in
|
|
each dimension) at most 512 times. If atoms move through the periodic
|
|
box more than this many times, the image flags will "roll over",
|
|
e.g. from 511 to -512, which can cause diagnostics like the
|
|
mean-squared displacement, as calculated by the "compute
|
|
msd"_compute_msd.html command, to be faulty.
|
|
|
|
To allow for larger atomic systems with atom IDs or larger molecular
|
|
systems or larger image flags, compile with -DLAMMPS_BIGBIG. This
|
|
stores atom IDs and image flags in 64-bit integers. This enables
|
|
atomic or molecular systems with atom IDS of up to 2^63 atoms (about
|
|
9e18). And image flags will not "roll over" until they reach 2^20 =
|
|
1048576.
|
|
|
|
If your system does not support 8-byte integers, you will need to
|
|
compile with the -DLAMMPS_SMALLSMALL setting. This will restrict the
|
|
total number of atoms (for atomic or molecular systems) and timesteps
|
|
to 2^31 (about 2 billion). Image flags will roll over at 2^9 = 512.
|
|
|
|
Note that in src/lmptype.h there are definitions of all these data
|
|
types as well as the MPI data types associated with them. The MPI
|
|
types need to be consistent with the associated C data types, or else
|
|
LAMMPS will generate a run-time error. As far as we know, the
|
|
settings defined in src/lmptype.h are portable and work on every
|
|
current system.
|
|
|
|
In all cases, the size of problem that can be run on a per-processor
|
|
basis is limited by 4-byte integer storage to 2^31 atoms per processor
|
|
(about 2 billion). This should not normally be a limitation since such
|
|
a problem would have a huge per-processor memory footprint due to
|
|
neighbor lists and would run very slowly in terms of CPU secs/timestep.
|
|
|
|
:line
|
|
|
|
[{Building for a Mac:}] :link(start_2_5)
|
|
|
|
OS X is BSD Unix, so it should just work. See the
|
|
src/MAKE/MACHINES/Makefile.mac and Makefile.mac_mpi files.
|
|
|
|
:line
|
|
|
|
[{Building for Windows:}] :link(start_2_6)
|
|
|
|
The LAMMPS download page has an option to download both a serial and
|
|
parallel pre-built Windows executable. See the "Running
|
|
LAMMPS"_#start_6 section for instructions on running these executables
|
|
on a Windows box.
|
|
|
|
The pre-built executables hosted on the "LAMMPS download
|
|
page"_http://lammps.sandia.gov/download.html are built with a subset
|
|
of the available packages; see the download page for the list. These
|
|
are single executable files. No examples or documentation in
|
|
included. You will need to download the full source code package to
|
|
obtain those.
|
|
|
|
As an alternative, you can download "daily builds" (and some older
|
|
versions) of the installer packages from
|
|
"rpm.lammps.org/windows.html"_http://rpm.lammps.org/windows.html.
|
|
These executables are built with most optional packages and the
|
|
download includes documentation, some tools and most examples.
|
|
|
|
If you want a Windows version with specific packages included and
|
|
excluded, you can build it yourself.
|
|
|
|
One way to do this is install and use cygwin to build LAMMPS with a
|
|
standard unix style make program, just as you would on a Linux box;
|
|
see src/MAKE/MACHINES/Makefile.cygwin.
|
|
|
|
The other way to do this is using Visual Studio and project files.
|
|
See the src/WINDOWS directory and its README.txt file for instructions
|
|
on both a basic build and a customized build with pacakges you select.
|
|
|
|
:line
|
|
|
|
2.3 Making LAMMPS with optional packages :h4,link(start_3)
|
|
|
|
This section has the following sub-sections:
|
|
|
|
"Package basics"_#start_3_1
|
|
"Including/excluding packages"_#start_3_2
|
|
"Packages that require extra libraries"_#start_3_3
|
|
"Packages that require Makefile.machine settings"_#start_3_4 :ul
|
|
|
|
Note that the following "Section 2.4"_#start_4 describes the Make.py
|
|
tool which can be used to install/un-install packages and build the
|
|
auxiliary libraries which some of them use. It can also auto-edit a
|
|
Makefile.machine to add settings needed by some packages.
|
|
|
|
:line
|
|
|
|
[{Package basics:}] :link(start_3_1)
|
|
|
|
The source code for LAMMPS is structured as a set of core files which
|
|
are always included, plus optional packages. Packages are groups of
|
|
files that enable a specific set of features. For example, force
|
|
fields for molecular systems or granular systems are in packages.
|
|
|
|
You can see the list of all packages by typing "make package" from
|
|
within the src directory of the LAMMPS distribution. This also lists
|
|
various make commands that can be used to manipulate packages.
|
|
|
|
If you use a command in a LAMMPS input script that is specific to a
|
|
particular package, you must have built LAMMPS with that package, else
|
|
you will get an error that the style is invalid or the command is
|
|
unknown. Every command's doc page specfies if it is part of a
|
|
package. You can also type
|
|
|
|
lmp_machine -h :pre
|
|
|
|
to run your executable with the optional "-h command-line
|
|
switch"_#start_7 for "help", which will list the styles and commands
|
|
known to your executable.
|
|
|
|
There are two kinds of packages in LAMMPS, standard and user packages.
|
|
More information about the contents of standard and user packages is
|
|
given in "Section_packages"_Section_packages.html of the manual. The
|
|
difference between standard and user packages is as follows:
|
|
|
|
Standard packages are supported by the LAMMPS developers and are
|
|
written in a syntax and style consistent with the rest of LAMMPS.
|
|
This means we will answer questions about them, debug and fix them if
|
|
necessary, and keep them compatible with future changes to LAMMPS.
|
|
|
|
User packages have been contributed by users, and always begin with
|
|
the user prefix. If they are a single command (single file), they are
|
|
typically in the user-misc package. Otherwise, they are a a set of
|
|
files grouped together which add a specific functionality to the code.
|
|
|
|
User packages don't necessarily meet the requirements of the standard
|
|
packages. If you have problems using a feature provided in a user
|
|
package, you will likely need to contact the contributor directly to
|
|
get help. Information on how to submit additions you make to LAMMPS
|
|
as a user-contributed package is given in "this
|
|
section"_Section_modify.html#mod_15 of the documentation.
|
|
|
|
Some packages (both standard and user) require additional libraries.
|
|
See more details below.
|
|
|
|
:line
|
|
|
|
[{Including/excluding packages:}] :link(start_3_2)
|
|
|
|
To use or not use a package you must include or exclude it before
|
|
building LAMMPS. From the src directory, this is typically as simple
|
|
as:
|
|
|
|
make yes-colloid
|
|
make g++ :pre
|
|
|
|
or
|
|
|
|
make no-manybody
|
|
make g++ :pre
|
|
|
|
IMPORTANT NOTE: You should NOT include/exclude packages and build
|
|
LAMMPS in a single make command by using multiple targets, e.g. make
|
|
yes-colloid g++. This is because the make procedure creates a list of
|
|
source files that will be out-of-date for the build if the package
|
|
configuration changes during the same command.
|
|
|
|
Some packages have individual files that depend on other packages
|
|
being included. LAMMPS checks for this and does the right thing.
|
|
I.e. individual files are only included if their dependencies are
|
|
already included. Likewise, if a package is excluded, other files
|
|
dependent on that package are also excluded.
|
|
|
|
If you will never run simulations that use the features in a
|
|
particular packages, there is no reason to include it in your build.
|
|
For some packages, this will keep you from having to build auxiliary
|
|
libraries (see below), and will also produce a smaller executable
|
|
which may run a bit faster.
|
|
|
|
When you download a LAMMPS tarball, these packages are pre-installed
|
|
in the src directory: KSPACE, MANYBODY,MOLECULE. When you download
|
|
LAMMPS source files from the SVN or Git repositories, no packages are
|
|
pre-installed.
|
|
|
|
Packages are included or excluded by typing "make yes-name" or "make
|
|
no-name", where "name" is the name of the package in lower-case, e.g.
|
|
name = kspace for the KSPACE package or name = user-atc for the
|
|
USER-ATC package. You can also type "make yes-standard", "make
|
|
no-standard", "make yes-std", "make no-std", "make yes-user", "make
|
|
no-user", "make yes-all" or "make no-all" to include/exclude various
|
|
sets of packages. Type "make package" to see the all of the
|
|
package-related make options.
|
|
|
|
IMPORTANT NOTE: Inclusion/exclusion of a package works by simply
|
|
moving files back and forth between the main src directory and
|
|
sub-directories with the package name (e.g. src/KSPACE, src/USER-ATC),
|
|
so that the files are seen or not seen when LAMMPS is built. After
|
|
you have included or excluded a package, you must re-build LAMMPS.
|
|
|
|
Additional package-related make options exist to help manage LAMMPS
|
|
files that exist in both the src directory and in package
|
|
sub-directories. You do not normally need to use these commands
|
|
unless you are editing LAMMPS files or have downloaded a patch from
|
|
the LAMMPS WWW site.
|
|
|
|
Typing "make package-update" or "make pu" will overwrite src files
|
|
with files from the package sub-directories if the package has been
|
|
included. It should be used after a patch is installed, since patches
|
|
only update the files in the package sub-directory, but not the src
|
|
files. Typing "make package-overwrite" will overwrite files in the
|
|
package sub-directories with src files.
|
|
|
|
Typing "make package-status" or "make ps" will show which packages are
|
|
currently included. Of those that are included, it will list files
|
|
that are different in the src directory and package sub-directory.
|
|
Typing "make package-diff" lists all differences between these files.
|
|
Again, type "make package" to see all of the package-related make
|
|
options.
|
|
|
|
:line
|
|
|
|
[{Packages that require extra libraries:}] :link(start_3_3)
|
|
|
|
A few of the standard and user packages require additional auxiliary
|
|
libraries. They must be compiled first, before LAMMPS is built. If
|
|
you get a LAMMPS build error about a missing library, this is likely
|
|
the reason. See the "Section_packages"_Section_packages.html doc page
|
|
for a list of packages that have auxiliary libraries.
|
|
|
|
Code for most of these auxiliary libraries is included in the LAMMPS
|
|
distribution under the lib directory. Examples are the USER-ATC and
|
|
MEAM packages. A few auxiliary libraries are NOT included with
|
|
LAMMPS; to use the associated package you must download and install
|
|
the auxiliary library yourself. Examples are the KIM and VORONOI and
|
|
USER-MOLFILE packages.
|
|
|
|
For provided libraries, each lib directory has a README file
|
|
(e.g. lib/reax/README) with instructions on how to build that library.
|
|
Typically this is done by typing something like:
|
|
|
|
make -f Makefile.g++ :pre
|
|
|
|
If one of the provided Makefiles is not appropriate for your system
|
|
you will need to edit or add one. Note that all the Makefiles have a
|
|
setting for EXTRAMAKE at the top that specifies a Makefile.lammps.*
|
|
file.
|
|
|
|
If the library build is successful, it will produce 2 files in the lib
|
|
directory:
|
|
|
|
libpackage.a
|
|
Makefile.lammps :pre
|
|
|
|
The Makefile.lammps file will be a copy of the EXTRAMAKE file setting
|
|
specified in the library Makefile.* you used.
|
|
|
|
Note that you must insure that the settings in Makefile.lammps are
|
|
appropriate for your system. If they are not, the LAMMPS build will
|
|
fail.
|
|
|
|
As explained in the lib/package/README files, the settings in
|
|
Makefile.lammps are used to specify additional system libraries and
|
|
their locations so that LAMMPS can build with the auxiliary library.
|
|
For example, if the MEAM or REAX packages are used, the auxiliary
|
|
libraries consist of F90 code, built with a Fortran complier. To link
|
|
that library with LAMMPS (a C++ code) via whatever C++ compiler LAMMPS
|
|
is built with, typically requires additional Fortran-to-C libraries be
|
|
included in the link. Another example are the BLAS and LAPACK
|
|
libraries needed to use the USER-ATC or USER-AWPMD packages.
|
|
|
|
For libraries without provided source code, the file
|
|
src/package/README has information on where to find the library and
|
|
how to build it, e.g. src/VORONOI/README. There is also a
|
|
Makefile.lammps file in the src/package directory. E.g. files
|
|
src/KIM/Makefile.lammps or src/VORONOI/Makefile.lammps or
|
|
src/UESR-MOLFILE/Makefile.lammps. These files serve the same purpose
|
|
as the lib/package/Makefile.lammps files described above. The files
|
|
have settings needed when LAMMPS is built to link with the
|
|
corresponding auxiliary library.
|
|
|
|
Again, you must insure that the settings in
|
|
src/package/Makefile.lammps are appropriate for your system and where
|
|
you installed the auxiliary library. If they are not, the LAMMPS
|
|
build will typically fail.
|
|
|
|
:line
|
|
|
|
[{Packages that require Makefile.machine settings}] :link(start_3_4)
|
|
|
|
A few packages require specific settings in Makefile.machine, to
|
|
either build or use the package effectively. These are the
|
|
USER-INTEL, KOKKOS, USER-OMP, and OPT packages. The details of what
|
|
flags to add or what variables to define are given on the doc pages
|
|
that describe each of these accelerator packages in detail:
|
|
|
|
"USER-INTEL package"_accelerate_intel.html
|
|
"KOKKOS package"_accelerate_kokkos.html
|
|
"USER-OMP package"_accelerate_omp.html
|
|
"OPT package"_accelerate_opt.html :ul
|
|
|
|
Here is a brief summary of what Makefile.machine changes are needed.
|
|
Note that the Make.py tool, described in the next "Section
|
|
2.4"_#start_4 can automatically add the needed info to an existing
|
|
machine Makefile, using simple command-line arguments.
|
|
|
|
In src/MAKE/OPTIONS see the following Makefiles for examples of the
|
|
changes described below:
|
|
|
|
Makefile.intel_cpu
|
|
Makefile.intel_phi
|
|
Makefile.kokkos_omp
|
|
Makefile.kokkos_cuda
|
|
Makefile.kokkos_phi
|
|
Makefile.omp :ul
|
|
|
|
For the USER-INTEL package, you have 2 choices when building. You can
|
|
build with CPU or Phi support. The latter uses Xeon Phi chips in
|
|
"offload" mode. Each of these modes requires additional settings in
|
|
your Makefile.machine for CCFLAGS and LINKFLAGS.
|
|
|
|
For CPU mode (if using an Intel compiler):
|
|
|
|
CCFLAGS: add -fopenmp, -DLAMMPS_MEMALIGN=64, -restrict, -xHost, -fno-alias, -ansi-alias, -override-limits
|
|
LINKFLAGS: add -fopenmp :ul
|
|
|
|
For Phi mode add the following in addition to the CPU mode flags:
|
|
|
|
CCFLAGS: add -DLMP_INTEL_OFFLOAD and
|
|
LINKFLAGS: add -offload :ul
|
|
|
|
And also add this to CCFLAGS:
|
|
|
|
-offload-option,mic,compiler,"-fp-model fast=2 -mGLOB_default_function_attrs=\"gather_scatter_loop_unroll=4\"" :pre
|
|
|
|
For the KOKKOS package, you have 3 choices when building. You can
|
|
build with OMP or Cuda or Phi support. Phi support uses Xeon Phi
|
|
chips in "native" mode. This can be done by setting the following
|
|
variables in your Makefile.machine:
|
|
|
|
for OMP support, set OMP = yes
|
|
for Cuda support, set OMP = yes and CUDA = yes
|
|
for Phi support, set OMP = yes and MIC = yes :ul
|
|
|
|
These can also be set as additional arguments to the make command, e.g.
|
|
|
|
make g++ OMP=yes MIC=yes :pre
|
|
|
|
Building the KOKKOS package with CUDA support requires a Makefile
|
|
machine that uses the NVIDIA "nvcc" compiler, as well as an
|
|
appropriate "arch" setting appropriate to the GPU hardware and NVIDIA
|
|
software you have on your machine. See
|
|
src/MAKE/OPTIONS/Makefile.kokkos_cuda for an example of such a machine
|
|
Makefile.
|
|
|
|
For the USER-OMP package, your Makefile.machine needs additional
|
|
settings for CCFLAGS and LINKFLAGS.
|
|
|
|
CCFLAGS: add -fopenmp and -restrict
|
|
LINKFLAGS: add -fopenmp :ul
|
|
|
|
For the OPT package, your Makefile.machine needs an additional
|
|
settings for CCFLAGS.
|
|
|
|
CCFLAGS: add -restrict :ul
|
|
|
|
:line
|
|
|
|
2.4 Building LAMMPS via the Make.py script :h4,link(start_4)
|
|
|
|
The src directory includes a Make.py script, written in Python, which
|
|
can be used to automate various steps of the build process. It is
|
|
particularly useful for working with the accelerator packages, as well
|
|
as other packages which require auxiliary libraries to be built.
|
|
|
|
You can run Make.py from the src directory by typing either:
|
|
|
|
Make.py -h
|
|
python Make.py -h :pre
|
|
|
|
which will give you help info about the tool. For the former to work,
|
|
you may need to edit the first line of Make.py to point to your local
|
|
Python. And you may need to insure the script is executable:
|
|
|
|
chmod +x Make.py :pre
|
|
|
|
Here are examples of build tasks you can perform with Make.py:
|
|
|
|
Install/uninstall packages: Make.py -p no-lib kokkos omp intel
|
|
Build specific auxiliary libs: Make.py lib-atc lib-meam
|
|
Build libs for all installed packages: Make.py -p cuda gpu -gpu mode=double arch=31 lib-all
|
|
Create a Makefile from scratch with a compiler and MPI: Make.py -m none -cc g++ -mpi mpich file
|
|
Augment Makefile.serial with settings for installed packages: Make.py -p intel -intel cpu -m serial file
|
|
Add JPG and FFTW support to Makefile.mpi: Make.py -m mpi -jpg -fft fftw file
|
|
Build LAMMPS with a parallel make using Makefile.mpi: Make.py -j 16 -m mpi exe
|
|
Build LAMMPS and libs it needs using Makefile.serial with accelerator settings: Make.py -p gpu intel -intel cpu lib-all file serial :tb(s=:)
|
|
|
|
The bench and examples directories give Make.py commands that can be
|
|
used to build LAMMPS with the various packages and options needed to
|
|
run all the benchmark and example input scripts. See these files for
|
|
more details:
|
|
|
|
bench/README
|
|
bench/FERMI/README
|
|
bench/KEPLER/README
|
|
bench/PHI/README
|
|
examples/README
|
|
examples/accelerate/README
|
|
examples/accelerate/make.list :ul
|
|
|
|
All of the Make.py options and syntax help can be accessed by using
|
|
the "-h" switch.
|
|
|
|
E.g. typing "Make.py -h" gives
|
|
|
|
Syntax: Make.py switch args ... {action1} {action2} ...
|
|
actions:
|
|
lib-all, lib-dir, clean, file, exe or machine
|
|
zero or more actions, in any order (machine must be last)
|
|
switches:
|
|
-d (dir), -j (jmake), -m (makefile), -o (output),
|
|
-p (packages), -r (redo), -s (settings), -v (verbose)
|
|
switches for libs:
|
|
-atc, -awpmd, -colvars, -cuda
|
|
-gpu, -meam, -poems, -qmmm, -reax
|
|
switches for build and makefile options:
|
|
-intel, -kokkos, -cc, -mpi, -fft, -jpg, -png :pre
|
|
|
|
Using the "-h" switch with other switches and actions gives additional
|
|
info on all the other specified switches or actions. The "-h" can be
|
|
anywhere in the command-line and the other switches do not need their
|
|
arguments. E.g. type "Make.py -h -d -atc -intel" will print:
|
|
|
|
-d dir
|
|
dir = LAMMPS home dir
|
|
if -d not specified, working dir must be lammps/src :pre
|
|
|
|
-atc make=suffix lammps=suffix2
|
|
all args are optional and can be in any order
|
|
make = use Makefile.suffix (def = g++)
|
|
lammps = use Makefile.lammps.suffix2 (def = EXTRAMAKE in makefile) :pre
|
|
|
|
-intel mode
|
|
mode = cpu or phi (def = cpu)
|
|
build Intel package for CPU or Xeon Phi :pre
|
|
|
|
Note that Make.py never overwrites an existing Makefile.machine.
|
|
Instead, it creates src/MAKE/MINE/Makefile.auto, which you can save or
|
|
rename if desired. Likewise it creates an executable named
|
|
src/lmp_auto, which you can rename using the -o switch if desired.
|
|
|
|
The most recently executed Make.py commmand is saved in
|
|
src/Make.py.last. You can use the "-r" switch (for redo) to re-invoke
|
|
the last command, or you can save a sequence of one or more Make.py
|
|
commands to a file and invoke the file of commands using "-r". You
|
|
can also label the commands in the file and invoke one or more of them
|
|
by name.
|
|
|
|
A typical use of Make.py is to start with a valid Makefile.machine for
|
|
your system, that works for a vanilla LAMMPS build, i.e. when optional
|
|
packages are not installed. You can then use Make.py to add various
|
|
settings (FFT, JPG, PNG) to the Makefile.machine as well as change its
|
|
compiler and MPI options. You can also add additional packages to the
|
|
build, as well as build the needed supporting libraries.
|
|
|
|
You can also use Make.py to create a new Makefile.machine from
|
|
scratch, using the "-m none" switch, if you also specify what compiler
|
|
and MPI options to use, via the "-cc" and "-mpi" switches.
|
|
|
|
:line
|
|
|
|
2.5 Building LAMMPS as a library :h4,link(start_5)
|
|
|
|
LAMMPS can be built as either a static or shared library, which can
|
|
then be called from another application or a scripting language. See
|
|
"this section"_Section_howto.html#howto_10 for more info on coupling
|
|
LAMMPS to other codes. See "this section"_Section_python.html for
|
|
more info on wrapping and running LAMMPS from Python.
|
|
|
|
[Static library:] :h5
|
|
|
|
To build LAMMPS as a static library (*.a file on Linux), type
|
|
|
|
make makelib
|
|
make -f Makefile.lib foo :pre
|
|
|
|
where foo is the machine name. This kind of library is typically used
|
|
to statically link a driver application to LAMMPS, so that you can
|
|
insure all dependencies are satisfied at compile time. Note that
|
|
inclusion or exclusion of any desired optional packages should be done
|
|
before typing "make makelib". The first "make" command will create a
|
|
current Makefile.lib with all the file names in your src dir. The
|
|
second "make" command will use it to build LAMMPS as a static library,
|
|
using the ARCHIVE and ARFLAGS settings in src/MAKE/Makefile.foo. The
|
|
build will create the file liblammps_foo.a which another application can
|
|
link to.
|
|
|
|
[Shared library:] :h5
|
|
|
|
To build LAMMPS as a shared library (*.so file on Linux), which can be
|
|
dynamically loaded, e.g. from Python, type
|
|
|
|
make makeshlib
|
|
make -f Makefile.shlib foo :pre
|
|
|
|
where foo is the machine name. This kind of library is required when
|
|
wrapping LAMMPS with Python; see "Section_python"_Section_python.html
|
|
for details. Again, note that inclusion or exclusion of any desired
|
|
optional packages should be done before typing "make makelib". The
|
|
first "make" command will create a current Makefile.shlib with all the
|
|
file names in your src dir. The second "make" command will use it to
|
|
build LAMMPS as a shared library, using the SHFLAGS and SHLIBFLAGS
|
|
settings in src/MAKE/Makefile.foo. The build will create the file
|
|
liblammps_foo.so which another application can link to dyamically. It
|
|
will also create a soft link liblammps.so, which the Python wrapper uses
|
|
by default.
|
|
|
|
Note that for a shared library to be usable by a calling program, all
|
|
the auxiliary libraries it depends on must also exist as shared
|
|
libraries. This will be the case for libraries included with LAMMPS,
|
|
such as the dummy MPI library in src/STUBS or any package libraries in
|
|
lib/packges, since they are always built as shared libraries with the
|
|
-fPIC switch. However, if a library like MPI or FFTW does not exist
|
|
as a shared library, the second make command will generate an error.
|
|
This means you will need to install a shared library version of the
|
|
package. The build instructions for the library should tell you how
|
|
to do this.
|
|
|
|
As an example, here is how to build and install the "MPICH
|
|
library"_mpich, a popular open-source version of MPI, distributed by
|
|
Argonne National Labs, as a shared library in the default
|
|
/usr/local/lib location:
|
|
|
|
:link(mpich,http://www-unix.mcs.anl.gov/mpi)
|
|
|
|
./configure --enable-shared
|
|
make
|
|
make install :pre
|
|
|
|
You may need to use "sudo make install" in place of the last line if
|
|
you do not have write privileges for /usr/local/lib. The end result
|
|
should be the file /usr/local/lib/libmpich.so.
|
|
|
|
[Additional requirement for using a shared library:] :h5
|
|
|
|
The operating system finds shared libraries to load at run-time using
|
|
the environment variable LD_LIBRARY_PATH. So you may wish to copy the
|
|
file src/liblammps.so or src/liblammps_g++.so (for example) to a place
|
|
the system can find it by default, such as /usr/local/lib, or you may
|
|
wish to add the LAMMPS src directory to LD_LIBRARY_PATH, so that the
|
|
current version of the shared library is always available to programs
|
|
that use it.
|
|
|
|
For the csh or tcsh shells, you would add something like this to your
|
|
~/.cshrc file:
|
|
|
|
setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:/home/sjplimp/lammps/src :pre
|
|
|
|
[Calling the LAMMPS library:] :h5
|
|
|
|
Either flavor of library (static or shared0 allows one or more LAMMPS
|
|
objects to be instantiated from the calling program.
|
|
|
|
When used from a C++ program, all of LAMMPS is wrapped in a LAMMPS_NS
|
|
namespace; you can safely use any of its classes and methods from
|
|
within the calling code, as needed.
|
|
|
|
When used from a C or Fortran program or a scripting language like
|
|
Python, the library has a simple function-style interface, provided in
|
|
src/library.cpp and src/library.h.
|
|
|
|
See the sample codes in examples/COUPLE/simple for examples of C++ and
|
|
C and Fortran codes that invoke LAMMPS thru its library interface.
|
|
There are other examples as well in the COUPLE directory which are
|
|
discussed in "Section_howto 10"_Section_howto.html#howto_10 of the
|
|
manual. See "Section_python"_Section_python.html of the manual for a
|
|
description of the Python wrapper provided with LAMMPS that operates
|
|
through the LAMMPS library interface.
|
|
|
|
The files src/library.cpp and library.h define the C-style API for
|
|
using LAMMPS as a library. See "Section_howto
|
|
19"_Section_howto.html#howto_19 of the manual for a description of the
|
|
interface and how to extend it for your needs.
|
|
|
|
:line
|
|
|
|
2.6 Running LAMMPS :h4,link(start_6)
|
|
|
|
By default, LAMMPS runs by reading commands from standard input. Thus
|
|
if you run the LAMMPS executable by itself, e.g.
|
|
|
|
lmp_linux :pre
|
|
|
|
it will simply wait, expecting commands from the keyboard. Typically
|
|
you should put commands in an input script and use I/O redirection,
|
|
e.g.
|
|
|
|
lmp_linux < in.file :pre
|
|
|
|
For parallel environments this should also work. If it does not, use
|
|
the '-in' command-line switch, e.g.
|
|
|
|
lmp_linux -in in.file :pre
|
|
|
|
"This section"_Section_commands.html describes how input scripts are
|
|
structured and what commands they contain.
|
|
|
|
You can test LAMMPS on any of the sample inputs provided in the
|
|
examples or bench directory. Input scripts are named in.* and sample
|
|
outputs are named log.*.name.P where name is a machine and P is the
|
|
number of processors it was run on.
|
|
|
|
Here is how you might run a standard Lennard-Jones benchmark on a
|
|
Linux box, using mpirun to launch a parallel job:
|
|
|
|
cd src
|
|
make linux
|
|
cp lmp_linux ../bench
|
|
cd ../bench
|
|
mpirun -np 4 lmp_linux < in.lj :pre
|
|
|
|
See "this page"_bench for timings for this and the other benchmarks on
|
|
various platforms. Note that some of the example scripts require
|
|
LAMMPS to be built with one or more of its optional packages.
|
|
|
|
:link(bench,http://lammps.sandia.gov/bench.html)
|
|
|
|
:line
|
|
|
|
On a Windows box, you can skip making LAMMPS and simply download an
|
|
executable, as described above, though the pre-packaged executables
|
|
include only certain packages.
|
|
|
|
To run a LAMMPS executable on a Windows machine, first decide whether
|
|
you want to download the non-MPI (serial) or the MPI (parallel)
|
|
version of the executable. Download and save the version you have
|
|
chosen.
|
|
|
|
For the non-MPI version, follow these steps:
|
|
|
|
Get a command prompt by going to Start->Run... ,
|
|
then typing "cmd". :ulb,l
|
|
|
|
Move to the directory where you have saved lmp_win_no-mpi.exe
|
|
(e.g. by typing: cd "Documents"). :l
|
|
|
|
At the command prompt, type "lmp_win_no-mpi -in in.lj", replacing in.lj
|
|
with the name of your LAMMPS input script. :l,ule
|
|
|
|
For the MPI version, which allows you to run LAMMPS under Windows on
|
|
multiple processors, follow these steps:
|
|
|
|
Download and install
|
|
"MPICH2"_http://www.mcs.anl.gov/research/projects/mpich2/downloads/index.php?s=downloads
|
|
for Windows. :ulb,l
|
|
|
|
You'll need to use the mpiexec.exe and smpd.exe files from the MPICH2
|
|
package. Put them in same directory (or path) as the LAMMPS Windows
|
|
executable. :l
|
|
|
|
Get a command prompt by going to Start->Run... ,
|
|
then typing "cmd". :l
|
|
|
|
Move to the directory where you have saved lmp_win_mpi.exe
|
|
(e.g. by typing: cd "Documents"). :l
|
|
|
|
Then type something like this: "mpiexec -localonly 4 lmp_win_mpi -in
|
|
in.lj", replacing in.lj with the name of your LAMMPS input script. :l
|
|
|
|
Note that you may need to provide smpd with a passphrase (it doesn't
|
|
matter what you type). :l
|
|
|
|
In this mode, output may not immediately show up on the screen, so if
|
|
your input script takes a long time to execute, you may need to be
|
|
patient before the output shows up. :l Alternatively, you can still
|
|
use this executable to run on a single processor by typing something
|
|
like: "lmp_win_mpi -in in.lj". :l,ule
|
|
|
|
:line
|
|
|
|
The screen output from LAMMPS is described in the next section. As it
|
|
runs, LAMMPS also writes a log.lammps file with the same information.
|
|
|
|
Note that this sequence of commands copies the LAMMPS executable
|
|
(lmp_linux) to the directory with the input files. This may not be
|
|
necessary, but some versions of MPI reset the working directory to
|
|
where the executable is, rather than leave it as the directory where
|
|
you launch mpirun from (if you launch lmp_linux on its own and not
|
|
under mpirun). If that happens, LAMMPS will look for additional input
|
|
files and write its output files to the executable directory, rather
|
|
than your working directory, which is probably not what you want.
|
|
|
|
If LAMMPS encounters errors in the input script or while running a
|
|
simulation it will print an ERROR message and stop or a WARNING
|
|
message and continue. See "Section_errors"_Section_errors.html for a
|
|
discussion of the various kinds of errors LAMMPS can or can't detect,
|
|
a list of all ERROR and WARNING messages, and what to do about them.
|
|
|
|
LAMMPS can run a problem on any number of processors, including a
|
|
single processor. In theory you should get identical answers on any
|
|
number of processors and on any machine. In practice, numerical
|
|
round-off can cause slight differences and eventual divergence of
|
|
molecular dynamics phase space trajectories.
|
|
|
|
LAMMPS can run as large a problem as will fit in the physical memory
|
|
of one or more processors. If you run out of memory, you must run on
|
|
more processors or setup a smaller problem.
|
|
|
|
:line
|
|
|
|
2.7 Command-line options :h4,link(start_7)
|
|
|
|
At run time, LAMMPS recognizes several optional command-line switches
|
|
which may be used in any order. Either the full word or a one-or-two
|
|
letter abbreviation can be used:
|
|
|
|
-c or -cuda
|
|
-e or -echo
|
|
-h or -help
|
|
-i or -in
|
|
-k or -kokkos
|
|
-l or -log
|
|
-nc or -nocite
|
|
-pk or -package
|
|
-p or -partition
|
|
-pl or -plog
|
|
-ps or -pscreen
|
|
-r or -restart
|
|
-ro or -reorder
|
|
-sc or -screen
|
|
-sf or -suffix
|
|
-v or -var :ul
|
|
|
|
For example, lmp_ibm might be launched as follows:
|
|
|
|
mpirun -np 16 lmp_ibm -v f tmp.out -l my.log -sc none < in.alloy
|
|
mpirun -np 16 lmp_ibm -var f tmp.out -log my.log -screen none < in.alloy :pre
|
|
|
|
Here are the details on the options:
|
|
|
|
-cuda on/off :pre
|
|
|
|
Explicitly enable or disable CUDA support, as provided by the
|
|
USER-CUDA package. Even if LAMMPS is built with this package, as
|
|
described above in "Section 2.3"_#start_3, this switch must be set to
|
|
enable running with the CUDA-enabled styles the package provides. If
|
|
the switch is not set (the default), LAMMPS will operate as if the
|
|
USER-CUDA package were not installed; i.e. you can run standard LAMMPS
|
|
or with the GPU package, for testing or benchmarking purposes.
|
|
|
|
-echo style :pre
|
|
|
|
Set the style of command echoing. The style can be {none} or {screen}
|
|
or {log} or {both}. Depending on the style, each command read from
|
|
the input script will be echoed to the screen and/or logfile. This
|
|
can be useful to figure out which line of your script is causing an
|
|
input error. The default value is {log}. The echo style can also be
|
|
set by using the "echo"_echo.html command in the input script itself.
|
|
|
|
-help :pre
|
|
|
|
Print a brief help summary and a list of options compiled into this
|
|
executable for each LAMMPS style (atom_style, fix, compute,
|
|
pair_style, bond_style, etc). This can tell you if the command you
|
|
want to use was included via the appropriate package at compile time.
|
|
LAMMPS will print the info and immediately exit if this switch is
|
|
used.
|
|
|
|
-in file :pre
|
|
|
|
Specify a file to use as an input script. This is an optional switch
|
|
when running LAMMPS in one-partition mode. If it is not specified,
|
|
LAMMPS reads its script from standard input, typically from a script
|
|
via I/O redirection; e.g. lmp_linux < in.run. I/O redirection should
|
|
also work in parallel, but if it does not (in the unlikely case that
|
|
an MPI implementation does not support it), then use the -in flag.
|
|
Note that this is a required switch when running LAMMPS in
|
|
multi-partition mode, since multiple processors cannot all read from
|
|
stdin.
|
|
|
|
-kokkos on/off keyword/value ... :pre
|
|
|
|
Explicitly enable or disable KOKKOS support, as provided by the KOKKOS
|
|
package. Even if LAMMPS is built with this package, as described
|
|
above in "Section 2.3"_#start_3, this switch must be set to enable
|
|
running with the KOKKOS-enabled styles the package provides. If the
|
|
switch is not set (the default), LAMMPS will operate as if the KOKKOS
|
|
package were not installed; i.e. you can run standard LAMMPS or with
|
|
the GPU or USER-CUDA or USER-OMP packages, for testing or benchmarking
|
|
purposes.
|
|
|
|
Additional optional keyword/value pairs can be specified which
|
|
determine how Kokkos will use the underlying hardware on your
|
|
platform. These settings apply to each MPI task you launch via the
|
|
"mpirun" or "mpiexec" command. You may choose to run one or more MPI
|
|
tasks per physical node. Note that if you are running on a desktop
|
|
machine, you typically have one physical node. On a cluster or
|
|
supercomputer there may be dozens or 1000s of physical nodes.
|
|
|
|
Either the full word or an abbreviation can be used for the keywords.
|
|
Note that the keywords do not use a leading minus sign. I.e. the
|
|
keyword is "t", not "-t". Also note that each of the keywords has a
|
|
default setting. Example of when to use these options and what
|
|
settings to use on different platforms is given in "Section
|
|
5.8"_Section_accelerate.html#acc_8.
|
|
|
|
d or device
|
|
g or gpus
|
|
t or threads
|
|
n or numa :ul
|
|
|
|
device Nd :pre
|
|
|
|
This option is only relevant if you built LAMMPS with CUDA=yes, you
|
|
have more than one GPU per node, and if you are running with only one
|
|
MPI task per node. The Nd setting is the ID of the GPU on the node to
|
|
run on. By default Nd = 0. If you have multiple GPUs per node, they
|
|
have consecutive IDs numbered as 0,1,2,etc. This setting allows you
|
|
to launch multiple independent jobs on the node, each with a single
|
|
MPI task per node, and assign each job to run on a different GPU.
|
|
|
|
gpus Ng Ns :pre
|
|
|
|
This option is only relevant if you built LAMMPS with CUDA=yes, you
|
|
have more than one GPU per node, and you are running with multiple MPI
|
|
tasks per node (up to one per GPU). The Ng setting is how many GPUs
|
|
you will use. The Ns setting is optional. If set, it is the ID of a
|
|
GPU to skip when assigning MPI tasks to GPUs. This may be useful if
|
|
your desktop system reserves one GPU to drive the screen and the rest
|
|
are intended for computational work like running LAMMPS. By default
|
|
Ng = 1 and Ns is not set.
|
|
|
|
Depending on which flavor of MPI you are running, LAMMPS will look for
|
|
one of these 3 environment variables
|
|
|
|
SLURM_LOCALID (various MPI variants compiled with SLURM support)
|
|
MV2_COMM_WORLD_LOCAL_RANK (Mvapich)
|
|
OMPI_COMM_WORLD_LOCAL_RANK (OpenMPI) :pre
|
|
|
|
which are initialized by the "srun", "mpirun" or "mpiexec" commands.
|
|
The environment variable setting for each MPI rank is used to assign a
|
|
unique GPU ID to the MPI task.
|
|
|
|
threads Nt :pre
|
|
|
|
This option assigns Nt number of threads to each MPI task for
|
|
performing work when Kokkos is executing in OpenMP or pthreads mode.
|
|
The default is Nt = 1, which essentially runs in MPI-only mode. If
|
|
there are Np MPI tasks per physical node, you generally want Np*Nt =
|
|
the number of physical cores per node, to use your available hardware
|
|
optimally. This also sets the number of threads used by the host when
|
|
LAMMPS is compiled with CUDA=yes.
|
|
|
|
numa Nm :pre
|
|
|
|
This option is only relevant when using pthreads with hwloc support.
|
|
In this case Nm defines the number of NUMA regions (typicaly sockets)
|
|
on a node which will be utilizied by a single MPI rank. By default Nm
|
|
= 1. If this option is used the total number of worker-threads per
|
|
MPI rank is threads*numa. Currently it is always almost better to
|
|
assign at least one MPI rank per NUMA region, and leave numa set to
|
|
its default value of 1. This is because letting a single process span
|
|
multiple NUMA regions induces a significant amount of cross NUMA data
|
|
traffic which is slow.
|
|
|
|
-log file :pre
|
|
|
|
Specify a log file for LAMMPS to write status information to. In
|
|
one-partition mode, if the switch is not used, LAMMPS writes to the
|
|
file log.lammps. If this switch is used, LAMMPS writes to the
|
|
specified file. In multi-partition mode, if the switch is not used, a
|
|
log.lammps file is created with hi-level status information. Each
|
|
partition also writes to a log.lammps.N file where N is the partition
|
|
ID. If the switch is specified in multi-partition mode, the hi-level
|
|
logfile is named "file" and each partition also logs information to a
|
|
file.N. For both one-partition and multi-partition mode, if the
|
|
specified file is "none", then no log files are created. Using a
|
|
"log"_log.html command in the input script will override this setting.
|
|
Option -plog will override the name of the partition log files file.N.
|
|
|
|
-nocite :pre
|
|
|
|
Disable writing the log.cite file which is normally written to list
|
|
references for specific cite-able features used during a LAMMPS run.
|
|
See the "citation page"_http://lammps.sandia.gov/cite.html for more
|
|
details.
|
|
|
|
-package style args .... :pre
|
|
|
|
Invoke the "package"_package.html command with style and args. The
|
|
syntax is the same as if the command appeared at the top of the input
|
|
script. For example "-package gpu 2" or "-pk gpu 2" is the same as
|
|
"package gpu 2"_package.html in the input script. The possible styles
|
|
and args are documented on the "package"_package.html doc page. This
|
|
switch can be used multiple times, e.g. to set options for the
|
|
USER-INTEL and USER-OMP packages which can be used together.
|
|
|
|
Along with the "-suffix" command-line switch, this is a convenient
|
|
mechanism for invoking accelerator packages and their options without
|
|
having to edit an input script.
|
|
|
|
-partition 8x2 4 5 ... :pre
|
|
|
|
Invoke LAMMPS in multi-partition mode. When LAMMPS is run on P
|
|
processors and this switch is not used, LAMMPS runs in one partition,
|
|
i.e. all P processors run a single simulation. If this switch is
|
|
used, the P processors are split into separate partitions and each
|
|
partition runs its own simulation. The arguments to the switch
|
|
specify the number of processors in each partition. Arguments of the
|
|
form MxN mean M partitions, each with N processors. Arguments of the
|
|
form N mean a single partition with N processors. The sum of
|
|
processors in all partitions must equal P. Thus the command
|
|
"-partition 8x2 4 5" has 10 partitions and runs on a total of 25
|
|
processors.
|
|
|
|
Running with multiple partitions can e useful for running
|
|
"multi-replica simulations"_Section_howto.html#howto_5, where each
|
|
replica runs on on one or a few processors. Note that with MPI
|
|
installed on a machine (e.g. your desktop), you can run on more
|
|
(virtual) processors than you have physical processors.
|
|
|
|
To run multiple independent simulatoins from one input script, using
|
|
multiple partitions, see "Section_howto 4"_Section_howto.html#howto_4
|
|
of the manual. World- and universe-style "variables"_variable.html
|
|
are useful in this context.
|
|
|
|
-plog file :pre
|
|
|
|
Specify the base name for the partition log files, so partition N
|
|
writes log information to file.N. If file is none, then no partition
|
|
log files are created. This overrides the filename specified in the
|
|
-log command-line option. This option is useful when working with
|
|
large numbers of partitions, allowing the partition log files to be
|
|
suppressed (-plog none) or placed in a sub-directory (-plog
|
|
replica_files/log.lammps) If this option is not used the log file for
|
|
partition N is log.lammps.N or whatever is specified by the -log
|
|
command-line option.
|
|
|
|
-pscreen file :pre
|
|
|
|
Specify the base name for the partition screen file, so partition N
|
|
writes screen information to file.N. If file is none, then no
|
|
partition screen files are created. This overrides the filename
|
|
specified in the -screen command-line option. This option is useful
|
|
when working with large numbers of partitions, allowing the partition
|
|
screen files to be suppressed (-pscreen none) or placed in a
|
|
sub-directory (-pscreen replica_files/screen). If this option is not
|
|
used the screen file for partition N is screen.N or whatever is
|
|
specified by the -screen command-line option.
|
|
|
|
-restart restartfile {remap} datafile keyword value ... :pre
|
|
|
|
Convert the restart file into a data file and immediately exit. This
|
|
is the same operation as if the following 2-line input script were
|
|
run:
|
|
|
|
read_restart restartfile {remap}
|
|
write_data datafile keyword value ... :pre
|
|
|
|
Note that the specified restartfile and datafile can have wild-card
|
|
characters ("*",%") as described by the
|
|
"read_restart"_read_restart.html and "write_data"_write_data.html
|
|
commands. But a filename such as file.* will need to be enclosed in
|
|
quotes to avoid shell expansion of the "*" character.
|
|
|
|
Note that following restartfile, the optional flag {remap} can be
|
|
used. This has the same effect as adding it to the
|
|
"read_restart"_read_restart.html command, as explained on its doc
|
|
page. This is only useful if the reading of the restart file triggers
|
|
an error that atoms have been lost. In that case, use of the remap
|
|
flag should allow the data file to still be produced.
|
|
|
|
Also note that following datafile, the same optional keyword/value
|
|
pairs can be listed as used by the "write_data"_write_data.html
|
|
command.
|
|
|
|
-reorder nth N
|
|
-reorder custom filename :pre
|
|
|
|
Reorder the processors in the MPI communicator used to instantiate
|
|
LAMMPS, in one of several ways. The original MPI communicator ranks
|
|
all P processors from 0 to P-1. The mapping of these ranks to
|
|
physical processors is done by MPI before LAMMPS begins. It may be
|
|
useful in some cases to alter the rank order. E.g. to insure that
|
|
cores within each node are ranked in a desired order. Or when using
|
|
the "run_style verlet/split"_run_style.html command with 2 partitions
|
|
to insure that a specific Kspace processor (in the 2nd partition) is
|
|
matched up with a specific set of processors in the 1st partition.
|
|
See the "Section_accelerate"_Section_accelerate.html doc pages for
|
|
more details.
|
|
|
|
If the keyword {nth} is used with a setting {N}, then it means every
|
|
Nth processor will be moved to the end of the ranking. This is useful
|
|
when using the "run_style verlet/split"_run_style.html command with 2
|
|
partitions via the -partition command-line switch. The first set of
|
|
processors will be in the first partition, the 2nd set in the 2nd
|
|
partition. The -reorder command-line switch can alter this so that
|
|
the 1st N procs in the 1st partition and one proc in the 2nd partition
|
|
will be ordered consecutively, e.g. as the cores on one physical node.
|
|
This can boost performance. For example, if you use "-reorder nth 4"
|
|
and "-partition 9 3" and you are running on 12 processors, the
|
|
processors will be reordered from
|
|
|
|
0 1 2 3 4 5 6 7 8 9 10 11 :pre
|
|
|
|
to
|
|
|
|
0 1 2 4 5 6 8 9 10 3 7 11 :pre
|
|
|
|
so that the processors in each partition will be
|
|
|
|
0 1 2 4 5 6 8 9 10
|
|
3 7 11 :pre
|
|
|
|
See the "processors" command for how to insure processors from each
|
|
partition could then be grouped optimally for quad-core nodes.
|
|
|
|
If the keyword is {custom}, then a file that specifies a permutation
|
|
of the processor ranks is also specified. The format of the reorder
|
|
file is as follows. Any number of initial blank or comment lines
|
|
(starting with a "#" character) can be present. These should be
|
|
followed by P lines of the form:
|
|
|
|
I J :pre
|
|
|
|
where P is the number of processors LAMMPS was launched with. Note
|
|
that if running in multi-partition mode (see the -partition switch
|
|
above) P is the total number of processors in all partitions. The I
|
|
and J values describe a permutation of the P processors. Every I and
|
|
J should be values from 0 to P-1 inclusive. In the set of P I values,
|
|
every proc ID should appear exactly once. Ditto for the set of P J
|
|
values. A single I,J pairing means that the physical processor with
|
|
rank I in the original MPI communicator will have rank J in the
|
|
reordered communicator.
|
|
|
|
Note that rank ordering can also be specified by many MPI
|
|
implementations, either by environment variables that specify how to
|
|
order physical processors, or by config files that specify what
|
|
physical processors to assign to each MPI rank. The -reorder switch
|
|
simply gives you a portable way to do this without relying on MPI
|
|
itself. See the "processors out"_processors command for how to output
|
|
info on the final assignment of physical processors to the LAMMPS
|
|
simulation domain.
|
|
|
|
-screen file :pre
|
|
|
|
Specify a file for LAMMPS to write its screen information to. In
|
|
one-partition mode, if the switch is not used, LAMMPS writes to the
|
|
screen. If this switch is used, LAMMPS writes to the specified file
|
|
instead and you will see no screen output. In multi-partition mode,
|
|
if the switch is not used, hi-level status information is written to
|
|
the screen. Each partition also writes to a screen.N file where N is
|
|
the partition ID. If the switch is specified in multi-partition mode,
|
|
the hi-level screen dump is named "file" and each partition also
|
|
writes screen information to a file.N. For both one-partition and
|
|
multi-partition mode, if the specified file is "none", then no screen
|
|
output is performed. Option -pscreen will override the name of the
|
|
partition screen files file.N.
|
|
|
|
-suffix style :pre
|
|
|
|
Use variants of various styles if they exist. The specified style can
|
|
be {cuda}, {gpu}, {intel}, {kk}, {omp}, or {opt}. These refer to
|
|
optional packages that LAMMPS can be built with, as described above in
|
|
"Section 2.3"_#start_3. The "cuda" style corresponds to the USER-CUDA
|
|
package, the "gpu" style to the GPU package, the "intel" style to the
|
|
USER-INTEL package, the "kk" style to the KOKKOS package, the "opt"
|
|
style to the OPT package, and the "omp" style to the USER-OMP package.
|
|
|
|
Along with the "-package" command-line switch, this is a convenient
|
|
mechanism for invoking accelerator packages and their options without
|
|
having to edit an input script.
|
|
|
|
As an example, all of the packages provide a "pair_style
|
|
lj/cut"_pair_lj.html variant, with style names lj/cut/cuda,
|
|
lj/cut/gpu, lj/cut/intel, lj/cut/kk, lj/cut/omp, and lj/cut/opt. A
|
|
variant style can be specified explicitly in your input script,
|
|
e.g. pair_style lj/cut/gpu. If the -suffix switch is used the
|
|
specified suffix (cuda,gpu,intel,kk,omp,opt) is automatically appended
|
|
whenever your input script command creates a new
|
|
"atom"_atom_style.html, "pair"_pair_style.html, "fix"_fix.html,
|
|
"compute"_compute.html, or "run"_run_style.html style. If the variant
|
|
version does not exist, the standard version is created.
|
|
|
|
For the GPU package, using this command-line switch also invokes the
|
|
default GPU settings, as if the command "package gpu 1" were used at
|
|
the top of your input script. These settings can be changed by using
|
|
the "-package gpu" command-line switch or the "package
|
|
gpu"_package.html command in your script.
|
|
|
|
For the USER-INTEL package, using this command-line switch also
|
|
invokes the default USER-INTEL settings, as if the command "package
|
|
intel 1" were used at the top of your input script. These settings
|
|
can be changed by using the "-package intel" command-line switch or
|
|
the "package intel"_package.html command in your script. If the
|
|
USER-OMP package is also installed, the intel suffix will make the omp
|
|
suffix a second choice, if a requested style is not available in the
|
|
USER-INTEL package. It will also invoke the default USER-OMP
|
|
settings, as if the command "package omp 0" were used at the top of
|
|
your input script. These settings can be changed by using the
|
|
"-package omp" command-line switch or the "package omp"_package.html
|
|
command in your script.
|
|
|
|
For the KOKKOS package, using this command-line switch also invokes
|
|
the default KOKKOS settings, as if the command "package kokkos" were
|
|
used at the top of your input script. These settings can be changed
|
|
by using the "-package kokkos" command-line switch or the "package
|
|
kokkos"_package.html command in your script.
|
|
|
|
For the OMP package, using this command-line switch also invokes the
|
|
default OMP settings, as if the command "package omp 0" were used at
|
|
the top of your input script. These settings can be changed by using
|
|
the "-package omp" command-line switch or the "package
|
|
omp"_package.html command in your script.
|
|
|
|
The "suffix"_suffix.html command can also be used within an input
|
|
script to set a suffix, or to turn off or back on any suffix setting
|
|
made via the command line.
|
|
|
|
-var name value1 value2 ... :pre
|
|
|
|
Specify a variable that will be defined for substitution purposes when
|
|
the input script is read. This switch can be used multiple times to
|
|
define multiple variables. "Name" is the variable name which can be a
|
|
single character (referenced as $x in the input script) or a full
|
|
string (referenced as $\{abc\}). An "index-style
|
|
variable"_variable.html will be created and populated with the
|
|
subsequent values, e.g. a set of filenames. Using this command-line
|
|
option is equivalent to putting the line "variable name index value1
|
|
value2 ..." at the beginning of the input script. Defining an index
|
|
variable as a command-line argument overrides any setting for the same
|
|
index variable in the input script, since index variables cannot be
|
|
re-defined. See the "variable"_variable.html command for more info on
|
|
defining index and other kinds of variables and "this
|
|
section"_Section_commands.html#cmd_2 for more info on using variables
|
|
in input scripts.
|
|
|
|
NOTE: Currently, the command-line parser looks for arguments that
|
|
start with "-" to indicate new switches. Thus you cannot specify
|
|
multiple variable values if any of they start with a "-", e.g. a
|
|
negative numeric value. It is OK if the first value1 starts with a
|
|
"-", since it is automatically skipped.
|
|
|
|
:line
|
|
|
|
2.8 LAMMPS screen output :h4,link(start_8)
|
|
|
|
As LAMMPS reads an input script, it prints information to both the
|
|
screen and a log file about significant actions it takes to setup a
|
|
simulation. When the simulation is ready to begin, LAMMPS performs
|
|
various initializations and prints the amount of memory (in MBytes per
|
|
processor) that the simulation requires. It also prints details of
|
|
the initial thermodynamic state of the system. During the run itself,
|
|
thermodynamic information is printed periodically, every few
|
|
timesteps. When the run concludes, LAMMPS prints the final
|
|
thermodynamic state and a total run time for the simulation. It then
|
|
appends statistics about the CPU time and storage requirements for the
|
|
simulation. An example set of statistics is shown here:
|
|
|
|
Loop time of 49.002 on 2 procs for 2004 atoms :pre
|
|
|
|
Pair time (%) = 35.0495 (71.5267)
|
|
Bond time (%) = 0.092046 (0.187841)
|
|
Kspce time (%) = 6.42073 (13.103)
|
|
Neigh time (%) = 2.73485 (5.5811)
|
|
Comm time (%) = 1.50291 (3.06703)
|
|
Outpt time (%) = 0.013799 (0.0281601)
|
|
Other time (%) = 2.13669 (4.36041) :pre
|
|
|
|
Nlocal: 1002 ave, 1015 max, 989 min
|
|
Histogram: 1 0 0 0 0 0 0 0 0 1
|
|
Nghost: 8720 ave, 8724 max, 8716 min
|
|
Histogram: 1 0 0 0 0 0 0 0 0 1
|
|
Neighs: 354141 ave, 361422 max, 346860 min
|
|
Histogram: 1 0 0 0 0 0 0 0 0 1 :pre
|
|
|
|
Total # of neighbors = 708282
|
|
Ave neighs/atom = 353.434
|
|
Ave special neighs/atom = 2.34032
|
|
Number of reneighborings = 42
|
|
Dangerous reneighborings = 2 :pre
|
|
|
|
The first section gives the breakdown of the CPU run time (in seconds)
|
|
into major categories. The second section lists the number of owned
|
|
atoms (Nlocal), ghost atoms (Nghost), and pair-wise neighbors stored
|
|
per processor. The max and min values give the spread of these values
|
|
across processors with a 10-bin histogram showing the distribution.
|
|
The total number of histogram counts is equal to the number of
|
|
processors.
|
|
|
|
The last section gives aggregate statistics for pair-wise neighbors
|
|
and special neighbors that LAMMPS keeps track of (see the
|
|
"special_bonds"_special_bonds.html command). The number of times
|
|
neighbor lists were rebuilt during the run is given as well as the
|
|
number of potentially "dangerous" rebuilds. If atom movement
|
|
triggered neighbor list rebuilding (see the
|
|
"neigh_modify"_neigh_modify.html command), then dangerous
|
|
reneighborings are those that were triggered on the first timestep
|
|
atom movement was checked for. If this count is non-zero you may wish
|
|
to reduce the delay factor to insure no force interactions are missed
|
|
by atoms moving beyond the neighbor skin distance before a rebuild
|
|
takes place.
|
|
|
|
If an energy minimization was performed via the
|
|
"minimize"_minimize.html command, additional information is printed,
|
|
e.g.
|
|
|
|
Minimization stats:
|
|
E initial, next-to-last, final = -0.895962 -2.94193 -2.94342
|
|
Gradient 2-norm init/final= 1920.78 20.9992
|
|
Gradient inf-norm init/final= 304.283 9.61216
|
|
Iterations = 36
|
|
Force evaluations = 177 :pre
|
|
|
|
The first line lists the initial and final energy, as well as the
|
|
energy on the next-to-last iteration. The next 2 lines give a measure
|
|
of the gradient of the energy (force on all atoms). The 2-norm is the
|
|
"length" of this force vector; the inf-norm is the largest component.
|
|
The last 2 lines are statistics on how many iterations and
|
|
force-evaluations the minimizer required. Multiple force evaluations
|
|
are typically done at each iteration to perform a 1d line minimization
|
|
in the search direction.
|
|
|
|
If a "kspace_style"_kspace_style.html long-range Coulombics solve was
|
|
performed during the run (PPPM, Ewald), then additional information is
|
|
printed, e.g.
|
|
|
|
FFT time (% of Kspce) = 0.200313 (8.34477)
|
|
FFT Gflps 3d 1d-only = 2.31074 9.19989 :pre
|
|
|
|
The first line gives the time spent doing 3d FFTs (4 per timestep) and
|
|
the fraction it represents of the total KSpace time (listed above).
|
|
Each 3d FFT requires computation (3 sets of 1d FFTs) and communication
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(transposes). The total flops performed is 5Nlog_2(N), where N is the
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number of points in the 3d grid. The FFTs are timed with and without
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the communication and a Gflop rate is computed. The 3d rate is with
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communication; the 1d rate is without (just the 1d FFTs). Thus you
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can estimate what fraction of your FFT time was spent in
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communication, roughly 75% in the example above.
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:line
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2.9 Tips for users of previous LAMMPS versions :h4,link(start_9)
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The current C++ began with a complete rewrite of LAMMPS 2001, which
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was written in F90. Features of earlier versions of LAMMPS are listed
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in "Section_history"_Section_history.html. The F90 and F77 versions
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(2001 and 99) are also freely distributed as open-source codes; check
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the "LAMMPS WWW Site"_lws for distribution information if you prefer
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those versions. The 99 and 2001 versions are no longer under active
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development; they do not have all the features of C++ LAMMPS.
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If you are a previous user of LAMMPS 2001, these are the most
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significant changes you will notice in C++ LAMMPS:
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(1) The names and arguments of many input script commands have
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changed. All commands are now a single word (e.g. read_data instead
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of read data).
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(2) All the functionality of LAMMPS 2001 is included in C++ LAMMPS,
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but you may need to specify the relevant commands in different ways.
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(3) The format of the data file can be streamlined for some problems.
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See the "read_data"_read_data.html command for details. The data file
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section "Nonbond Coeff" has been renamed to "Pair Coeff" in C++ LAMMPS.
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(4) Binary restart files written by LAMMPS 2001 cannot be read by C++
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|
LAMMPS with a "read_restart"_read_restart.html command. This is
|
|
because they were output by F90 which writes in a different binary
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format than C or C++ writes or reads. Use the {restart2data} tool
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|
provided with LAMMPS 2001 to convert the 2001 restart file to a text
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data file. Then edit the data file as necessary before using the C++
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LAMMPS "read_data"_read_data.html command to read it in.
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(5) There are numerous small numerical changes in C++ LAMMPS that mean
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|
you will not get identical answers when comparing to a 2001 run.
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However, your initial thermodynamic energy and MD trajectory should be
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close if you have setup the problem for both codes the same.
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