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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>
</CENTER>
<HR>
<H3>pair_style kim command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>pair_style kim virialmode model
</PRE>
<UL><LI>virialmode = KIMvirial or LAMMPSvirial
<LI>model = name of KIM model (potential)
</UL>
<P><B>Examples:</B>
</P>
<PRE>pair_style kim KIMvirial model_Ar_P_Morse
pair_coeff * * Ar Ar
</PRE>
<P><B>Description:</B>
</P>
<P>This pair style is a wrapper on the <A HREF = "https://openkim.org">Knowledge Base for Interatomic
Models (KIM)</A> repository of interatomic potentials,
so that they can be used by LAMMPS scripts.
</P>
<P>In KIM lingo, a potential is a "model" and a model contains both the
analytic formulas that define the potential as well as the parameters
needed to run it for one or more materials, including coefficients and
cutoffs.
</P>
<P>The argument <I>virialmode</I> determines how the global virial is
calculated. If <I>KIMvirial</I> is specified, the KIM model performs the
global virial calculation (if it knows how). If <I>LAMMPSvirial</I> is
specified, LAMMPS computes the global virial using its fdotr mechanism.
</P>
<P>The argument <I>model</I> is the name of the KIM model for a specific
potential as KIM defines it. In principle, LAMMPS can invoke any KIM
model. You should get an error or warning message from either LAMMPS
or KIM if there is an incompatibility.
</P>
<P>Only a single pair_coeff command is used with the <I>kim</I> style which
specifies the mapping of LAMMPS atom types to KIM elements. This is
done by specifying N additional arguments after the * * in the
pair_coeff command, where N is the number of LAMMPS atom types:
</P>
<UL><LI>N element names = mapping of KIM elements to atom types
</UL>
<P>As an example, imagine the KIM model supports Si and C atoms. If your
LAMMPS simulation has 4 atom types and you want the 1st 3 to be Si,
and the 4th to be C, you would use the following pair_coeff command:
</P>
<PRE>pair_coeff * * Si Si Si C
</PRE>
<P>The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
The first three Si arguments map LAMMPS atom types 1,2,3 to Si as
defined within KIM. The final C argument maps LAMMPS atom type 4 to C
as defined within KIM. If a mapping value is specified as NULL, the
mapping is not performed. This can only be used when a <I>kim</I>
potential is used as part of the <I>hybrid</I> pair style. The NULL values
are placeholders for atom types that will be used with other
potentials.
</P>
<HR>
<P>In addition to the usual LAMMPS error messages, the KIM library itself
may generate errors, which should be printed to the screen. In this
case it is also useful to check the kim.log file for additional error
information. This file kim.log should be generated in the same
directory where LAMMPS is running.
</P>
<HR>
<P>Here is information on how to build KIM for use with LAMMPS.
</P>
<P>The KIM API is available for download from <A HREF = "https://openkim.org">this
site</A>, namely https://openkim.org. The tarball
you download is "openkim-api-vX.X.X.tgz", which can be unpacked via
</P>
<PRE>tar xvfz openkim*tgz
</PRE>
<P>The openkim-api-vX.X.X/DOCS/ directory has further documentation. In
order to compile and install the KIM API follow the instructions found
in the file openkim-api-vX.X.X/INSTALL. (Don't forget to download and
compile any Model Drivers and Models that you want to use.)
</P>
<P>Once you have successfully compiled and installed the KIM API, you
need to set up LAMMPS to use your KIM API system. In the LAMMPS
package there is a directory src/KIM/ with an important file in it:
Makefile.lammps. When you do 'make yes-kim' LAMMPS will use the
settings in src/KIM/Makefile.lammps to find the KIM API header files
and the KIM API library itself for linking purposes. Thus, you should
edit src/KIM/Makefile.lammps to ensure it has the correct settings for
your system and your build of KIM.
</P>
<P>The following is an example of how to download, compile, and run
LAMMPS with the KIM API:
</P>
<pre>
mkdir lammps-kim
cd lammps-kim
#
# download lammps and the KIM API
#
wget http://lammps.sandia.gov/tars/lammps-DDMMMYY.tar.gz # replace DDMMMYY as appropriate here and below
wget http://s3.openkim.org/openkim-api/openkim-api-vX.X.X.tgz # replace X.X.X as appropriate here and below
tar zxvf openkim-api-vX.X.X.tgz
#
# Get OpenKIM models, setup and compile
#
cd openkim-api-vX.X.X
cp Makefile.KIM_Config.example Makefile.KIM_Config
vi Makefile.KIM_Config # edit file as appropriate following the instructions given in the INSTALL file
cd MODEL_DRIVERS
wget --content-disposition 'https://kim-items.openkim.org/archive?kimid=EAM_Dynamo__MD_120291908751_000&compression=gz'
tar zxvf EAM_Dynamo__MD_120291908751_000.tgz
cd ../MODELS
wget --content-disposition 'https://kim-items.openkim.org/archive?kimid=EAM_Dynamo_Angelo_Moody_NiAlH__MO_418978237058_000&compression=gz'
tar zxvf EAM_Dynamo_Angelo_Moody_NiAlH__MO_418978237058_000.tgz
cd ../
make
cd ../
#
# setup and compile lammps
#
tar zxvf lammps-DDMMMYY.tar.gz
cd lammps-DDMMMYY/src/KIM
vi Makefile.lammps # edit the three lines to look like below:
# kim_SYSINC = -I../../../openkim-api-vX.X.X/KIM_API
# kim_SYSLIB = -lkim
# kim_SYSPATH = -L../../../openkim-api-vX.X.X/KIM_API
cd ../
make yes-kim
cd STUBS
make
cd ../
make serial
#
# run simple example with KIM model
#
cd ../../
vi al-input # create file with the following content
#----------------------------------------------------------------------------------------
variable x index 1
variable y index 1
variable z index 1
variable xx equal 20*$x
variable yy equal 20*$y
variable zz equal 20*$z
units metal
atom_style atomic
lattice fcc 4.0500
region box block 0.0 ${xx} 0.0 ${yy} 0.0 ${zz}
create_box 1 box
create_atoms 1 box
pair_style kim KIMvirial EAM_Dynamo_Angelo_Moody_NiAlH__MO_418978237058_000
pair_coeff * * Al
mass 1 26.98
velocity all create 200.0 232345 loop geom
neighbor 0.3 bin
neigh_modify delay 0 every 1 check yes
fix 1 all nve
run 100
#----------------------------------------------------------------------------------------
./lammps-DDMMYY/src/lmp_serial < al-input
</pre>
<HR>
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
</P>
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
mix, shift, table, and tail options.
</P>
<P>This pair style does not write its information to <A HREF = "restart.html">binary restart
files</A>, since KIM stores the potential parameters.
Thus, you need to re-specify the pair_style and pair_coeff commands in
an input script that reads a restart file.
</P>
<P>This pair style can only be used via the <I>pair</I> keyword of the
<A HREF = "run_style.html">run_style respa</A> command. It does not support the
<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
</P>
<HR>
<P><B>Restrictions:</B>
</P>
<P>This pair style is part of the KIM package. It is only enabled if
LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
LAMMPS</A> section for more info.
</P>
<P>This current version of pair_style kim is compatible with the
openkim-api package version 1.2.0 and higher.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "pair_coeff.html">pair_coeff</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
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