forked from lijiext/lammps
44 lines
1.7 KiB
Plaintext
44 lines
1.7 KiB
Plaintext
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This directory has a code that shows how LAMMPS can be linked to a
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driver application as a library. The purpose is to illustrate how
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another code could perform computations while using LAMMPS to perform
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MD, or how an umbrella code or script could call both LAMMPS and some
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other code to perform a coupled calculation.
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Umbrella.cpp is the simple driving code that will call LAMMPS.
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LAMMPS must first be built as a library. See the "Making LAMMPS"
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section of Section_start.html in the documentation for info on how to
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do this. Basically, you type something like
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make makelib
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make -f Makefile.lib g++
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in the LAMMPS src directory to create liblmp_g++.a
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You can then build the umbrella code with a compile line something
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like this, which includes paths to the LAMMPS library interface, MPI,
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and FFTW.
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g++ -I/home/sjplimp/tools/mpich/include -I/home/sjplimp/lammps/src
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-L/home/sjplimp/lammps/src -L/home/sjplimp/tools/mpich/lib
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-L/home/sjplimp/tools/fftw/lib umbrella.cpp
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-llmp_g++ -lfftw -lmpich -o umbrella
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You then run umbrella on a parallel machine on some number
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of processors Q with 2 arguments:
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mpirun -np Q umbrella P in.lj
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P is the number of procs you want LAMMPS to run on (must be <= Q).
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In.lj is a LAMMPS input script.
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Umbrella will launch LAMMPS on P procs, read the input
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script a line at a time, and pass each command line to LAMMPS. The
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final line of the script is a "run" command, so LAMMPS will run
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the problem.
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Umbrella then requests all the atom coordinates from LAMMPS, moves one
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of the atoms a small amount "epsilon", passes the coordinates back to
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LAMMPS, and runs LAMMPS again. If you look at the output, you should
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see a small energy change between runs, due to the moved atom.
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