# 3.2. Build LAMMPS with make

Building LAMMPS with traditional makefiles requires that you have a Makefile.<machine> file appropriate for your system in either the src/MAKE, src/MAKE/MACHINES, src/MAKE/OPTIONS, or src/MAKE/MINE directory (see below). It can include various options for customizing your LAMMPS build with a number of global compilation options and features.

## 3.2.1. Requirements

Those makefiles are written for and tested with GNU make and may not be compatible with other make programs. In most cases, if the “make” program is not GNU make, then there will be a GNU make program available under the name “gmake”. If GNU make or a compatible make is not available, you may have to first install it or switch to building with CMake. The makefiles of the traditional make based build process and the scripts they are calling expect a few additional tools to be available and functioning.

• a working C/C++ compiler toolchain supporting the C++11 standard; on Linux these are often the GNU compilers. Some older compilers require adding flags like -std=c++11 to enable the C++11 mode.

• a Bourne shell compatible “Unix” shell program (often this is bash)

• a few shell utilities: ls, mv, ln, rm, grep, sed, tr, cat, touch, diff, dirname

• python (optional, required for make lib-<pkg> in the src folder). python scripts are currently tested with python 2.7 and 3.6. The procedure for building the documentation requires python 3.5 or later.

## 3.2.2. Getting started

To include LAMMPS packages (i.e. optional commands and styles) you must enable (or “install”) them first, as discussed on the Build package page. If a packages requires (provided or external) libraries, you must configure and build those libraries before building LAMMPS itself and especially before enabling such a package with make yes-<package>. Building LAMMPS with CMake can automate much of this for many types of machines, especially workstations, desktops, and laptops, so we suggest you try it first when building LAMMPS in those cases.

The commands below perform a default LAMMPS build, producing the LAMMPS executable lmp_serial and lmp_mpi in lammps/src:

cd lammps/src   # change to main LAMMPS source folder
make serial     # build a serial LAMMPS executable using GNU g++
make mpi        # build a parallel LAMMPS executable with MPI
make            # see a variety of make options


Compilation can take a long time, since LAMMPS is a large project with many features. If your machine has multiple CPU cores (most do these days), you can speed this up by compiling sources in parallel with make -j N (with N being the maximum number of concurrently executed tasks). Also installation of the ccache (= Compiler Cache) software may speed up repeated compilation even more, e.g. during code development.

After the initial build, whenever you edit LAMMPS source files, or add or remove new files to the source directory (e.g. by installing or uninstalling packages), you must re-compile and relink the LAMMPS executable with the same make <machine> command. The makefile’s dependency tracking should insure that only the necessary subset of files are re-compiled. If you change settings in the makefile, you have to recompile everything. To delete all objects you can use make clean-<machine>.

Note

Before the actual compilation starts, LAMMPS will perform several steps to collect information from the configuration and setup that is then embedded into the executable. When you build LAMMPS for the first time, it will also compile a tool to quickly assemble a list of dependencies, that are required for the make program to correctly detect which parts need to be recompiled after changes were made to the sources.

## 3.2.3. Customized builds and alternate makefiles

The src/MAKE directory tree contains the Makefile.<machine> files included in the LAMMPS distribution. Typing make example uses Makefile.example from one of those folders, if available. Thus the make serial and make mpi lines above use src/MAKE/Makefile.serial and src/MAKE/Makefile.mpi, respectively. Other makefiles are in these directories:

OPTIONS      # Makefiles which enable specific options
MACHINES     # Makefiles for specific machines
MINE         # customized Makefiles you create (you may need to create this folder)


Simply typing make lists all the available Makefile.<machine> files with a single line description toward the end of the output. A file with the same name can appear in multiple folders (not a good idea). The order the directories are searched is as follows: src/MAKE/MINE, src/MAKE, src/MAKE/OPTIONS, src/MAKE/MACHINES. This gives preference to a customized file you put in src/MAKE/MINE. If you create your own custom makefile under a new name, please edit the first line with the description and machine name, so you will not confuse yourself, when looking at the machine summary.

Makefiles you may wish to try include these (some require a package first be installed). Many of these include specific compiler flags for optimized performance. Please note, however, that some of these customized machine Makefile are contributed by users. Since both compilers, OS configurations, and LAMMPS itself keep changing, their settings may become outdated:

make mac             # build serial LAMMPS on a Mac
make mac_mpi         # build parallel LAMMPS on a Mac
make intel_cpu       # build with the USER-INTEL package optimized for CPUs
make knl             # build with the USER-INTEL package optimized for KNLs
make opt             # build with the OPT package optimized for CPUs
make omp             # build with the USER-OMP package optimized for OpenMP
make kokkos_omp      # build with the KOKKOS package for OpenMP
make kokkos_cuda_mpi # build with the KOKKOS package for GPUs
make kokkos_phi      # build with the KOKKOS package for KNLs