3.1. Build LAMMPS with CMake
This page describes how to use CMake in general to build LAMMPS. Details for specific compile time settings and options to enable and configure add-on packages are discussed with those packages. Links to those pages on the Build overview page.
The following text assumes some familiarity with CMake and focuses on
using the command line tool
cmake and what settings are supported
for building LAMMPS. A more detailed tutorial on how to use CMake
itself, the text mode or graphical user interface, to change the
generated output files for different build tools and development
environments is on a separate page.
LAMMPS currently requires that CMake version 3.10 or later is available; version 3.12 or later is preferred.
You must not mix the traditional make based
LAMMPS build procedure with using CMake. No packages may be
installed or a build been previously attempted in the LAMMPS source
directory by using
make <machine>. CMake will detect if this is
the case and generate an error. To remove conflicting files from the
src you can use the command
make no-all purge which will
uninstall all packages and delete all auto-generated files.
3.1.1. Advantages of using CMake
CMake is an alternative to compiling LAMMPS in the traditional way through (manually customized) makefiles and a recent addition to LAMMPS thanks to the efforts of Christoph Junghans (LANL) and Richard Berger (Temple U). Using CMake has multiple advantages that are specifically helpful for people with limited experience in compiling software or for people that want to modify or extend LAMMPS.
CMake can detect available hardware, tools, features, and libraries and adapt the LAMMPS default build configuration accordingly.
CMake can generate files for different build tools and integrated development environments (IDE).
CMake supports customization of settings with a command line, text mode, or graphical user interface. No knowledge of file formats or complex command line syntax is required.
All enabled components are compiled in a single build operation.
Automated dependency tracking for all files and configuration options.
Support for true out-of-source compilation. Multiple configurations and settings with different choices of LAMMPS packages, settings, or compilers can be configured and built concurrently from the same source tree.
Simplified packaging of LAMMPS for Linux distributions, environment modules, or automated build tools like Homebrew.
Integration of automated unit and regression testing (the LAMMPS side of this is still under active development).
3.1.2. Getting started
Building LAMMPS with CMake is a two-step process. In the first step,
you use CMake to generate a build environment in a new directory. For
that purpose you can use either the command-line utility
cmake3), the text-mode UI utility
ccmake3) or the
cmake-gui, or use them interchangeably. The
second step is then the compilation and linking of all objects,
libraries, and executables using the selected build tool. Here is a
minimal example using the command line version of CMake to build LAMMPS
with no add-on packages enabled and no customization:
cd lammps # change to the LAMMPS distribution directory mkdir build; cd build # create and use a build directory cmake ../cmake # configuration reading CMake scripts from ../cmake cmake --build . # compilation (or type "make")
This will create and change into a folder called
build, then run the
configuration step to generate build files for the default build command
and then launch that build command to compile LAMMPS. During the
configuration step CMake will try to detect whether support for MPI,
OpenMP, FFTW, gzip, JPEG, PNG, and ffmpeg are available and enable the
corresponding configuration settings. The progress of this
configuration can be followed on the screen and a summary of selected
options and settings will be printed at the end. The
. command will launch the compilation, which, if successful, will
ultimately produce a library
liblammps.a and the LAMMPS executable
lmp inside the
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). Installation of the ccache (= Compiler
Cache) software may speed up repeated compilation even more, e.g. during
code development, especially when repeatedly switching between branches.
After the initial build, whenever you edit LAMMPS source files, enable
or disable packages, change compiler flags or build options, you must
re-compile and relink the LAMMPS executable with
cmake --build . (or
make). If the compilation fails for some reason, try running
cmake . and then compile again. The included dependency tracking
should make certain that only the necessary subset of files is
re-compiled. You can also delete compiled objects, libraries, and
cmake --build . --target clean (or
After compilation, you may optionally install the LAMMPS executable into your system with:
make install # optional, copy compiled files into installation location
This will install the LAMMPS executable and library, some tools (if
configured) and additional files like LAMMPS API headers, manpages,
potential and force field files. The location of the installation tree
3.1.3. Configuration and build options
The CMake commands have one mandatory argument: a folder containing a
CMakeLists.txt (for LAMMPS it is located in the
cmake folder) or a build folder containing a file called
CMakeCache.txt, which is generated at the end of the CMake
configuration step. The cache file contains all current CMake settings.
To modify settings, enable or disable features, you need to set
variables with either the -D command line flag (
VARIABLE1_NAME=value) or change them in the text mode of the graphical
user interface. The -D flag can be used several times in one command.
For your convenience, we provide CMake presets
that combine multiple settings to enable optional LAMMPS packages or use
a different compiler tool chain. Those are loaded with the -C flag
-C ../cmake/presets/basic.cmake). This step would only be needed
once, as the settings from the preset files are stored in the
CMakeCache.txt file. It is also possible to customize the build
by adding one or more -D flags to the CMake command line.
Generating files for alternate build tools (e.g. Ninja) and project files
for IDEs like Eclipse, CodeBlocks, or Kate can be selected using the -G
command line flag. A list of available generator settings for your
specific CMake version is given when running
3.1.4. Multi-configuration build systems
Throughout this manual, it is mostly assumed that LAMMPS is being built
on a Unix-like operating system with “make” as the underlying “builder”,
since this is the most common case. In this case the build
“configuration” is chose using
<configuration> being one of “Release”, “Debug”,
“RelWithDebInfo”, or “MinSizeRel”. Some build tools, however, can also
use or even require having a so-called multi-configuration build system
setup. For a multi-configuration build, the built type (or
configuration) is selected at compile time using the same build
files. E.g. with:
cmake --build build-multi --config Release
In that case the resulting binaries are not in the build folder directly but in subdirectories corresponding to the build type (i.e. Release in the example from above). Similarly, for running unit tests the configuration is selected with the -C flag:
ctest -C Debug
The CMake scripts in LAMMPS have basic support for being compiled using a multi-config build system, but not all of it has been ported. This is in particular applicable to compiling packages that require additional libraries that would be downloaded and compiled by CMake. The “windows” preset file tries to keep track of which packages can be compiled natively with the MSVC compilers out-of-the box. Not all of those external libraries are portable to Windows, either.
3.1.5. Installing CMake
Check if your machine already has CMake installed:
which cmake # do you have it? which cmake3 # version 3 may have this name cmake --version # what specific version you have
On clusters or supercomputers which use environment modules to manage software packages, do this:
module list # is a module for cmake already loaded? module avail # is a module for cmake available? module load cmake # load cmake module with appropriate name
Most Linux distributions offer pre-compiled cmake packages through their package management system. If you do not have CMake or a recent enough version (Note: for CentOS 7.x you need to enable the EPEL repository), you can download the latest version from https://cmake.org/download/. Instructions on how to install it on various platforms can be found on this page.