LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel
Simulator.

It is a classical molecular dynamics simulation code designed to
run efficiently on parallel computers. It was developed at Sandia
National Laboratories, a US Department of Energy facility.

A basic installation of LAMMPS can be enhanced enabling the build of
internal or external extensions (packages) that add methods and/or
give support to third parts libraries or platforms.

Dependencies strictly needed to build LAMMPS with most internal 
packages enabled are already present in a full installation of 
Slackware 15.0 and the slackbuild can be launched without any other 
dependency not released with the official Slackware. Only openmpi is
highly recommended since LAMMPS takes advantage of the parallel 
computation. Furthermore some packages require it as strictly 
dependency. Instead of openmpi LAMMPS can be build with the support
of mpich, although the latter does not support the enabling of a 
package (OPENMP). If any MPI platform is found in the system, LAMMPS 
will be built anyway but with a reduced functionality.

Other optional dependencies available in Slackbuilds.org are 
autodetected and allow the enabling of some additional packages: HDF5,
OpenBLAS, python3-numpy, voro++, PLUMED, netcdf. Other packages need
third parts libraries given by downloaded extrafile and bundled in 
the application during the compilation. The slackbuild prevent the 
download during the build, so you have to download these extrafiles 
listed in lammps.info. Optional dependencies and the download of 
extrafiles are not needed if you do not require the respective 
packages. 

Warning: except to GPU, all packages are enabled by default if no 
dependencies are required (or they dependencies are found in the
system), but you have to disable the packages that require the 
extrafiles listed in lammps.info if you do not download them, 
otherwise the build fails during the check of cmake. 
For GPU package you can try:
   GPU=yes ./lammps.SlackBuild
or
   GPU=yes STATIC_OCL=yes ./lammps.SlackBuild
The latter uses an internal static OpenCL loader.

See README.SBo for a full list of available packages and their 
dependencies. 

Some packages available in the source of LAMMPS cannot be enabled for
reasons reported in README.SBo.