# suffix command

## Syntax

    suffix style args

-   style = *off* or *on* or *gpu* or *intel* or *kk* or *omp* or *opt*
    or *hybrid*
-   args = for hybrid style, default suffix to be used and alternative
    suffix

## Examples

``` LAMMPS
suffix off
suffix on
suffix gpu
suffix intel
suffix hybrid intel omp
suffix kk
```

## Description

This command allows you to use variants of various styles if they exist.
In that respect it operates the same as the [-suffix command-line
switch](Run_options). It also has options to turn off or back on any
suffix setting made via the command line.

The specified style can be *gpu*, *intel*, *kk*, *omp*, *opt* or
*hybrid*. These refer to optional packages that LAMMPS can be built
with, as described on the [Build package](Build_package) doc page. The
\"gpu\" style corresponds to the GPU package, the \"intel\" style to the
INTEL package, the \"kk\" style to the KOKKOS package, the \"omp\" style
to the OPENMP package, and the \"opt\" style to the OPT package.

These are the variants these packages provide:

-   GPU = a handful of pair styles and the PPPM kspace_style, optimized
    to run on one or more GPUs or multicore CPU/GPU nodes
-   INTEL = a collection of pair styles and neighbor routines optimized
    to run in single, mixed, or double precision on CPUs and Intel(R)
    Xeon Phi(TM) co-processors.
-   KOKKOS = a collection of atom, pair, and fix styles optimized to run
    using the Kokkos library on various kinds of hardware, including
    GPUs via CUDA and many-core chips via OpenMP or threading.
-   OPENMP = a collection of pair, bond, angle, dihedral, improper,
    kspace, compute, and fix styles with support for OpenMP
    multi-threading
-   OPT = a handful of pair styles, cache-optimized for faster CPU
    performance
-   HYBRID = a combination of two packages can be specified (see below)

As an example, all of the packages provide a [pair_style
lj/cut](pair_lj) variant, with style names lj/cut/opt, lj/cut/omp,
lj/cut/gpu, lj/cut/intel, or lj/cut/kk. A variant styles can be
specified explicitly in your input script, e.g. pair_style lj/cut/gpu.
If the suffix command is used with the appropriate style, you do not
need to modify your input script. The specified suffix
(opt,omp,gpu,intel,kk) is automatically appended whenever your input
script command creates a new [atom](atom_style), [pair](pair_style),
[bond](bond_style), [angle](angle_style), [dihedral](dihedral_style),
[improper](improper_style), [kspace](kspace_style), [fix](fix),
[compute](compute), or [run](run_style) style. If the variant version
does not exist, the standard version is created.

For \"hybrid\", two packages are specified. The first is used whenever
available. If a style with the first suffix is not available, the style
with the suffix for the second package will be used if available. For
example, \"hybrid intel omp\" will use styles from the INTEL package as
a first choice and styles from the OPENMP package as a second choice if
no INTEL variant is available.

If the specified style is *off*, then any previously specified suffix is
temporarily disabled, whether it was specified by a command-line switch
or a previous suffix command. If the specified style is *on*, a disabled
suffix is turned back on. The use of these 2 commands lets your input
script use a standard LAMMPS style (i.e. a non-accelerated variant),
which can be useful for testing or benchmarking purposes. Of course this
is also possible by not using any suffix commands, and explicitly
appending or not appending the suffix to the relevant commands in your
input script.

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

The default [run_style](run_style) verlet is invoked prior to reading
the input script and is therefore not affected by a suffix command in
the input script. The KOKKOS package requires \"run_style verlet/kk\",
so when using the KOKKOS package it is necessary to either use the
command line \"-sf kk\" command or add an explicit \"run_style verlet\"
command to the input script.
::::

## Restrictions

> none

## Related commands

[-suffix command-line switch](Run_options)

## Default

none