LAMMPS is a general-purpose molecular dynamics software package for massively parallel computers. It is written in an exceptionally clean style that makes it one of the most popular codes for users to extend and it currently has dozens of user-developed extensions.

For details about the code and its usage, see the LAMMPS home page. This page is dedicated to information pertaining to Theta at the ALCF.


ALCF does not officially support LAMMPS software, but provides assistance with compiling executables. For questions, contact us at

How to Obtain the Code

LAMMPS is an open-source code, which can be downloaded at

Building on Theta

After [LAMMPS] has been downloaded and unpacked, you should see a directory whose name is of the form lammps-<version>. Go to the directory lammps-<version>/src/MAKE/MACHINES and create a new Makefile.theta, as described below.

# theta = KNL, Intel compiler, MKL FFT

SHELL = /bin/sh

# ---------------------------------------------------------------------
# compiler/linker settings
# specify flags and libraries needed for your compiler

CC       = CC -mkl
OPTFLAGS = -xMIC-AVX512 -O3 -fp-model fast=2 -no-prec-div -qoverride-limits -DLAMMPS_MEMALIGN=64
CCFLAGS  = -g -qopenmp -DLAMMPS_MEMALIGN=64 -no-offload -fno-alias -ansi-alias -restrict $(OPTFLAGS)

LINK      = CC -mkl
LINKFLAGS = -g -qopenmp $(OPTFLAGS)
LIB       =
SIZE      = size

ARCHIVE    = ar
ARFLAGS    = -rc
SHLIBFLAGS = -shared

# ---------------------------------------------------------------------
# LAMMPS-specific settings, all OPTIONAL
# specify settings for LAMMPS features you will use
# if you change any -D setting, do full re-compile after "make clean"

# LAMMPS ifdef settings
# see possible settings in Section 2.2 (step 4) of manual


# MPI library
# see discussion in Section 2.2 (step 5) of manual
# MPI wrapper compiler/linker can provide this info
# can point to dummy MPI library in src/STUBS as in Makefile.serial
# use -D MPICH and OMPI settings in INC to avoid C++ lib conflicts
# INC = path for mpi.h, MPI compiler settings
# PATH = path for MPI library
# LIB = name of MPI library


# FFT library
# see discussion in Section 2.2 (step 6) of manaul
# can be left blank to use provided KISS FFT library
# INC = -DFFT setting, e.g. -DFFT_FFTW, FFT compiler settings
# PATH = path for FFT library
# LIB = name of FFT library

FFT_LIB  = -L$(MKLROOT)/lib/intel64 -Wl,--start-group -lmkl_intel_lp64 -lmkl_core -lmkl_intel_thread -Wl,--end-group -lpthread -lm -ldl

# JPEG and/or PNG library
# see discussion in Section 2.2 (step 7) of manual
# only needed if -DLAMMPS_JPEG or -DLAMMPS_PNG listed with LMP_INC
# INC = path(s) for jpeglib.h and/or png.h
# PATH = path(s) for JPEG library and/or PNG library
# LIB = name(s) of JPEG library and/or PNG library


# ---------------------------------------------------------------------
# build rules and dependencies
# do not edit this section

include Makefile.package.settings
include Makefile.package


# Path to src files

vpath %.cpp ..
vpath %.h ..

# Link target

$(EXE): $(OBJ)
	$(SIZE) $(EXE)

# Library targets

lib:    $(OBJ)

shlib:  $(OBJ)

# Compilation rules


	$(CC) $(CCFLAGS) $(EXTRA_INC) $(DEPFLAGS) $< > $@

# Individual dependencies

depend : fastdep.exe $(SRC)
	@./fastdep.exe $(EXTRA_INC) -- $^ > .depend || exit 1

fastdep.exe: ../DEPEND/fastdep.c
	cc -0 -o $@ $<

sinclude .depend

As newer versions of LAMMPS are distributed and changes made to the Makefile, the example Makefile above can be used to generate an updated Makefile using one of the Intel examples packaged with LAMMPS. With the Makefile in place, LAMMPS can be compiled from the lammps-<version>/src directory using the following command.

> make theta -j 16

Running LAMMPS Jobs on Theta

Following is an example executable script “run_lammps.csh” to run LAMMPS on two nodes of Theta with 64 MPI ranks per node. The job can be submitted with command “qsub run_lammps.csh”, where <project_name> is replaced with an active project allocation.

#COBALT -n 2 -t 10 -q debug-cache-quad -A <project_name> -O LAMMPS

aprun -n 128 -N 64 -d 1 --cc depth -e OMP_NUM_THREADS=1 -j 1 ./lmp_theta -in

Performance Notes

When possible, users will want to build LAMMPS executables with the USER-OMP and USER-INTEL packages for best performance on Theta. Following is an example script “run_lammps_intel.csh” to run LAMMPS on two nodes of Theta with 64 MPI ranks per node and two OpenMP threads per rank with the USER-INTEL and USER-OMP packages. The job can be submitted with command “qsub run_lammps_intel.csh.”

#COBALT -n 2 -t 10 -q debug-cache-quad -A <project_name> -O LAMMPS

aprun -n 128 -N 64 -d 2 --cc depth -e OMP_NUM_THREADS=2 -j 2 ./lmp_theta -in -sf hybrid intel omp

Not all available forcefields in LAMMPS are supported in one or both of these packages. For the latest information, please check LAMMPS website and documentation.