LAMMPS Intel(R) Package
                     --------------------------------
                     
             W. Michael Brown (Intel) michael.w.brown at intel.com
                  Markus Hohnerbach (RWTH Aachen University)
                   William McDoniel (RWTH Aachen University)
                   Rodrigo Canales (RWTH Aachen University)
                           Stan Moore (Sandia)
		   Ahmed E. Ismail (RWTH Aachen University)
                   Paolo Bientinesi (RWTH Aachen University)
                          Anupama Kurpad (Intel)
                          Biswajit Mishra (Shell)

This package provides LAMMPS styles that:

1. include support for single and mixed precision in addition to double.
2. include modifications to support vectorization for key routines
3. include modifications for data layouts to improve cache efficiency
4. include modifications to support offload to Intel(R) Xeon Phi(TM) coprocessors

For Intel server processors codenamed "Skylake", the following flags should be added or changed in the Makefile depending on the version:

2017 update 2 - No changes needed 2017 updates 3 or 4 - Use -xCOMMON-AVX512 and not -xHost or -xCORE-AVX512 2018 or newer - Use -xHost or -xCORE-AVX512 and -qopt-zmm-usage=high

When using the suffix command with "intel", intel styles will be used if they exist. If the suffix command is used with "hybrid intel omp" and the USER-OMP USER-OMP styles will be used whenever USER-INTEL styles are not available. This allow for running most styles in LAMMPS with threading.

The Long-Range Thread mode (LRT) in the Intel package currently uses pthreads by default. If pthreads are not supported in the build environment, the compile flag "-DLMP_INTEL_NOLRT" will disable the feature to allow for builds without pthreads. Alternatively, "-DLMP_INTEL_LRT11" can be used to build with compilers that support threads using the C++11 standard. When using LRT mode, you might need to disable OpenMP affinity settings (e.g. export KMP_AFFINITY=none). LAMMPS will generate a warning if the settings need to be changed.

In order to use offload to Intel(R) Xeon Phi(TM) coprocessors, the flag -DLMP_INTEL_OFFLOAD should be set in the Makefile. Offload requires the use of Intel compilers.

For portability reasons, vectorization directives are currently only enabled for Intel compilers. Using other compilers may result in significantly lower performance. This behavior can be changed by defining LMP_SIMD_COMPILER for the preprocessor (see intel_preprocess.h).

By default, when running with offload to Intel(R) coprocessors, affinity for host MPI tasks and OpenMP threads is set automatically within the code. This currently requires the use of system calls. To disable at build time, compile with -DINTEL_OFFLOAD_NOAFFINITY.

Vector intrinsics are temporarily being used for the Stillinger-Weber potential to allow for advanced features in the AVX512 instruction set to be exploited on early hardware. We hope to see compiler improvements for AVX512 that will eliminate this requirement, so it is not recommended to develop code based on the intrinsics implementation. Please e-mail the authors for more details.