forked from lijiext/lammps
129 lines
4.3 KiB
HTML
129 lines
4.3 KiB
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<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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</CENTER>
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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 model
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</PRE>
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<P>model = name of KIM model (potential)
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</P>
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<P><B>Examples:</B>
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</P>
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<PRE>pair_style kim model_Ar_P_Morse
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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 Knowledge Base for Interatomic
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Models (KIM) repository of interatomic potentials, so that they can be
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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>model</I> is the name of the model for a specific potential
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as KIM defines it. In principle, LAMMPS can invoke any KIM model.
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You should get an error message from either LAMMPS or KIM if there is
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an incompatibility.
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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 atoms 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 be used when a <I>kim</I> potential is
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used as part of the <I>hybrid</I> pair style. The NULL values are
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placeholders for atom types that will be used with other potentials.
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</P>
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<HR>
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<P>Where to look for error messages
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</P>
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<P>Some of the KIM models might fail to work with lammps. Check generated
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kim.log file for error messages.
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</P>
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<HR>
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<P>How to build KIM
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</P>
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<P>ENV variables
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</P>
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<P>setenv KIM_MODELS_DIR `pwd`/MODELs/
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setenv KIM_DIR `pwd`/
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setenv KIM_DYNAMIC yes
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</P>
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<P>It is required that OPENKIM directory with
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needed file structure is installed (can be downloaded from openkim.org)
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and needed environment variables are set:
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KIM_DIR = path openkim-api directory
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KIM_DYNAMIC -- if dynamic linking is used during building (default --static)
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KIM_MODELS_DIR = path to kim models directory (default -- $KIM_DIR/MODELs)
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See openkim-api/INSTALL for detailed instruction.
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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 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 pair style requires the <A HREF = "newton.html">newton</A> setting to be "off"
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for pair interactions.
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</P>
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<P>Currently this pair style only works with LAMMPS metal
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<A HREF = "units.html">units</A>, since KIM models are written using
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those units.
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</P>
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<P>Only KIM models that are using NEIGH-PURE-H, NEIGH-PURE-F and
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NEIGH-RVEC-F can be used with lammps. (see KIM documentation on NBC
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methods)
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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>, <A HREF = "pair_eam.html">pair_style eam</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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