# pair_style kim command

## Syntax

``` LAMMPS
pair_style kim model
```

model = name of a KIM model (the KIM ID for models archived in OpenKIM)

## Examples

``` LAMMPS
pair_style kim SW_StillingerWeber_1985_Si__MO_405512056662_005
pair_coeff * * Si
```

## Description

This pair style is a wrapper on the [Open Knowledgebase of Interatomic
Models (OpenKIM)](https://openkim.org)\_ repository of interatomic
potentials to enable their use in LAMMPS scripts.

The preferred interface for using interatomic models archived in OpenKIM
is the [kim command](kim_commands) interface. That interface supports
both \"KIM Portable Models\" (PMs) that conform to the KIM API Portable
Model Interface (PMI) and can be used by any simulation code that
conforms to the KIM API/PMI, and \"KIM Simulator Models\" (SMs) that are
natively implemented within a single simulation code (like LAMMPS) and
can only be used with it. The *pair_style kim* command is limited to KIM
PMs. It is used by the [kim command](kim_commands) interface as needed.

:::: note
::: title
Note
:::

Since *pair_style kim* is called by *kim interactions* as needed, it is
not recommended to be directly used in input scripts.
::::

------------------------------------------------------------------------

The argument *model* is the name of the KIM PM. For potentials archived
in OpenKIM this is the extended KIM ID (see [kim command](kim_commands)
for details). LAMMPS can invoke any KIM PM, however there can be
incompatibilities (for example due to unit matching issues). In the
event of an incompatibility, the code will terminate with an error
message. Check both the LAMMPS and KIM log files for details.

Only a single *pair_coeff* command is used with the *kim* style, which
specifies the mapping of LAMMPS atom types to the species supported by
the KIM PM. This is done by specifying *N* additional arguments after
the \* \* in the *pair_coeff* command, where *N* is the number of LAMMPS
atom types:

-   N element names = mapping of KIM elements to atom types

For example, consider a KIM PM that supports Si and C species. If the
LAMMPS simulation has four atom types, where the first three are Si, and
the fourth is C, the following *pair_coeff* command would be used:

``` LAMMPS
pair_coeff * * Si Si Si C
```

The first two arguments must be \* \* so as to span all LAMMPS atom
types. The first three Si arguments map LAMMPS atom types 1, 2, and 3 to
Si as defined within KIM PM. The final C argument maps LAMMPS atom type
4 to C.

------------------------------------------------------------------------

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. The file *kim.log* should be generated in the same
directory where LAMMPS is running.

To download, build, and install the KIM library on your system, see the
*lib/kim/README* file. Once you have done this and built LAMMPS with the
KIM package installed you can run the example input scripts in
*examples/kim*.

------------------------------------------------------------------------

## Mixing, shift, table, tail correction, restart, rRESPA info

This pair style does not support the [pair_modify](pair_modify) mix,
shift, table, and tail options.

This pair style does not write its information to [binary restart
files](restart), 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.

This pair style can only be used via the *pair* keyword of the
[run_style respa](run_style) command. It does not support the *inner*,
*middle*, *outer* keywords.

------------------------------------------------------------------------

## Restrictions

This pair style is part of the KIM package. See details on restrictions
in [kim command](kim_commands).

This current version of pair_style kim is compatible with the kim-api
package version 2.0.0 and higher.

## Related commands

[pair_coeff](pair_coeff), [kim command](kim_commands)

## Default

none