forked from lijiext/lammps
124 lines
4.6 KiB
HTML
124 lines
4.6 KiB
HTML
<HTML>
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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<HR>
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<H3>pair_style kim command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style kim virialmode model printflag
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</PRE>
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<UL><LI>virialmode = KIMvirial or LAMMPSvirial
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<LI>model = name of KIM model (potential)
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<LI>printflag = 1/0 do or do not print KIM descriptor file, optional
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>pair_style kim KIMvirial model_Ar_P_Morse
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pair_coeff * * Ar Ar
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</PRE>
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<PRE>pair_style kim KIMvirial model_Ar_P_Morse 1
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pair_coeff * * Ar Ar
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>This pair style is a wrapper on the <A HREF = "https://openkim.org">Knowledge Base for Interatomic
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Models (KIM)</A> repository of interatomic potentials,
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so that they can be used by LAMMPS scripts.
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</P>
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<P>In KIM lingo, a potential is a "model" and a model contains both the
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analytic formulas that define the potential as well as the parameters
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needed to run it for one or more materials, including coefficients and
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cutoffs.
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</P>
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<P>The argument <I>virialmode</I> determines how the global virial is
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calculated. If <I>KIMvirial</I> is specified, the KIM model performs the
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global virial calculation (if it knows how). If <I>LAMMPSvirial</I> is
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specified, LAMMPS computes the global virial using its fdotr mechanism.
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</P>
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<P>The argument <I>model</I> is the name of the KIM model for a specific
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potential as KIM defines it. In principle, LAMMPS can invoke any KIM
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model. You should get an error or warning message from either LAMMPS
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or KIM if there is an incompatibility.
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</P>
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<P>The argument <I>printflag</I> is optional. If it is set to a non-zero
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value then a KIM dsecriptor file is printed when KIM is invoked. This
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can be useful for debugging. The default is to not print this file.
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</P>
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<P>Only a single pair_coeff command is used with the <I>kim</I> style which
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specifies the mapping of LAMMPS atom types to KIM elements. This is
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done by specifying N additional arguments after the * * in the
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pair_coeff command, where N is the number of LAMMPS atom types:
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</P>
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<UL><LI>N element names = mapping of KIM elements to atom types
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</UL>
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<P>As an example, imagine the KIM model supports Si and C atoms. If your
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LAMMPS simulation has 4 atom types and you want the 1st 3 to be Si,
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and the 4th to be C, you would use the following pair_coeff command:
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</P>
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<PRE>pair_coeff * * Si Si Si C
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</PRE>
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<P>The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
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The first three Si arguments map LAMMPS atom types 1,2,3 to Si as
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defined within KIM. The final C argument maps LAMMPS atom type 4 to C
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as defined within KIM. If a mapping value is specified as NULL, the
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mapping is not performed. This can only be used when a <I>kim</I>
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potential is used as part of the <I>hybrid</I> pair style. The NULL values
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are placeholders for atom types that will be used with other
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potentials.
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</P>
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<HR>
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<P>In addition to the usual LAMMPS error messages, the KIM library itself
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may generate errors, which should be printed to the screen. In this
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case it is also useful to check the kim.log file for additional error
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information. This file kim.log should be generated in the same
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directory where LAMMPS is running.
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</P>
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<P>To download, build, and install the KIM library on your system, see
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the lib/kim/README file. Once you have done this and built LAMMPS
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with the KIM package installed you can run the example input scripts
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in examples/kim.
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</P>
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<HR>
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<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
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</P>
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<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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mix, shift, table, and tail options.
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</P>
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<P>This pair style does not write its information to <A HREF = "restart.html">binary restart
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files</A>, since KIM stores the potential parameters.
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Thus, you need to re-specify the pair_style and pair_coeff commands in
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an input script that reads a restart file.
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</P>
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<P>This pair style can only be used via the <I>pair</I> keyword of the
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<A HREF = "run_style.html">run_style respa</A> command. It does not support the
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<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
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</P>
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<HR>
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<P><B>Restrictions:</B>
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</P>
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<P>This pair style is part of the KIM package. It is only enabled if
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LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
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LAMMPS</A> section for more info.
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</P>
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<P>This current version of pair_style kim is compatible with the
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kim-api package version 1.6.0 and higher.
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "pair_coeff.html">pair_coeff</A>
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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