Gromacs
2024.4
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The GROMACS library (libgromacs
) provides a few different alternatives for using it. These are listed here from the highest level of abstraction to the low-level functions.
-h
output and command-line parsing yourself (possibly using classes that GROMACS provides).If these do not fit your needs, you may need to modify the GROMACS source code yourself. In particular, it is currently relatively difficult to extend the functionality of mdrun
without modifying the source code directly. If you think that some particular API would be necessary for your work, and think that it would be easy to expose, please drop a line on the developer discussion forum, or contribute the necessary changes on https://gitlab.com/gromacs/gromacs.
libgromacs
GROMACS is a bit picky on how the headers need to be used: depending on compilation options used for GROMACS, some preprocessor defines may need to be set, the required include path may also depend on compilation options, and some extra libraries may need to be linked. You will also likely need to use the same compiler (or sufficiently similar one that uses the same standard library) that was used to compile GROMACS.
To manage this more easily, GROMACS provides two mechanisms for getting the correct flags for compilation and linking against the GROMACS library:
pkg-config
: GROMACS installs libgromacs.pc
file (suffixed with the library suffix) for use with pkg-config
if that is present on the system. Sourcing GMXRC
adjusts the pkg-config
search path such that these files are found automatically. See Makefile.pkg
installed with the analysis template for one example of how to use it (to use it with a differently suffixed GROMACS, just replace libgromacs
with libgromacs
_suffix in the pkg-config
calls).find_package(GROMACS)
to work. See below for details about how to use this in CMake. Sourcing GMXRC
sets an environment variable that allows CMake to find the configuration file automatically. See CMakeLists.txt
installed with the analysis template for one example of how to use it.These mechanisms are currently provided on a best-effort basis, but are not routinely tested on a wide range of configurations. Please report any issues with details of how GROMACS was built so that the mechanism can be improved. Known issues:
pkg-config
files are not relocatable, i.e., they hard-code the installation prefix as an absolute path.BUILD_SHARED_LIBS
) from exactly the same version. There are several files that are shared between the installations in such a case, and the latter installation will overwrite those from the former.share/cmake/
from the installation directory before doing the install.install
target is used to install GROMACS over an existing installation, and the build type (e.g., Release vs. Debug) does not match what was previously installed, some obsolete CMake import target definition files are left behind in share/cmake/
, and may cause failures whey trying to use the package configuration files.GMX_BUILD_OWN_FFTW=ON
, the CMake-generated import definitions for libgromacs
reference a gmxfftw
target that was used in the build to reference the fftw
library. As this library only exists in the GROMACS build tree, and the CMake machinery does not write any import definitions for it anywhere, linking will fail with errors about not being able to find a gmxfftw
library. So the CMake package configuration files can only be used with GMX_BUILD_OWN_FFTW=OFF
.find_package(GROMACS)
details The CMake machinery to support find_package(GROMACS)
has two parts: a FindGROMACS.cmake
find module (found in share/gromacs/template/cmake/
in the installation and share/template/cmake/
in the source tree), and actual package configuration files (gromacs-config.cmake
and supporting files installed to share/cmake/
from input files in src/gromacs/
).
FindGROMACS.cmake
is a simple wrapper over the package configuration files, providing a somewhat more convenient interface to the machinery that supports multiple suffixed GROMACS installations in the same installation prefix (see GROMACS_SUFFIX
variable below). This file is intended to be version-agnostic and remain both forward- and backward-compatible even between major GROMACS releases. All version-specific information and the actual details about the compilation and linking settings is in the package configuration files. Build systems willing to utilize FindGROMACS.cmake
can create a local copy of it and use it like it is used in the installed share/gromacs/template/CMakeLists.txt
. The package configuration files can also be used directly if desired, bypassing FindGROMACS.cmake
.
Input options for influencing what to find:
GROMACS_SUFFIX
(only for FindGROMACS.cmake
) find_package(GROMACS)
to specify the GROMACS suffix to search for. If not set, an unsuffixed version is searched for. If using the package configuration files directly, the suffix must be set using find_package(GROMACS NAMES gromacs<suffix>)
. GROMACS_PREFER_STATIC
find_package(GROMACS)
to specify whether static or shared libraries are preferred if both are available. It does not affect which GROMACS installation is chosen, but if that installation has both static and shared libraries available (installed from two different builds with the same suffix), then this chooses the library to be returned in GROMACS_LIBRARIES
. GROMACS_DIR
find_package
, and can be used to specify a hint where to search for GROMACS. Also CMAKE_PREFIX_PATH
can be used for this purpose; see CMake documentation for find_package
for more details. GROMACS_DIR
can also be set as an environment variable, and this is done by GMXRC
. Output variables that specify how the found libgromacs
and header should be used:
GROMACS_INCLUDE_DIRS
GROMACS_LIBRARIES
libgromacs
. GROMACS_DEFINITIONS
-D
in front) that are required to compile the GROMACS headers. GROMACS_IS_DOUBLE
GROMACS_CXX_FLAGS
Additionally an imported target named Gromacs::libgromacs
is provided and can be used with target_link_libraries(foo PRIVATE Gromacs::libgromacs)
.
Declared macros/functions that can be used for checking for correctness of some settings:
gromacs_check_double(GMX_DOUBLE)
GMX_DOUBLE
should be the name of a cache variable that specified whether double-precision was requested. gromacs_check_compiler(LANG)
LANG=CXX
is supported. The headers for the public GROMACS API are installed in include/gromacs/
under the installation directory. The layout reflects the source code layout under the src/gromacs/
directory (see Source code layout). The headers directly under include/gromacs/
do not contain any declarations, but instead include a collection of headers from subdirectories. You should prefer to include these convenience headers instead of individual headers from the subdirectories, since they are much more stable. The individual headers in the subdirectories can be renamed or moved, but the goal is to only rarely change the name of these top-level headers.
Pre-5.0 versions of GROMACS installed (nearly) all headers directly under include/gromacs/
. Most of these headers still exist, but are no longer installed. The long-term goal is to reintroduce those parts of the API that make sense, but unfortunately this can take a long time. Thus, you should not expect much stability from the API in these headers.
For headers under other subdirectories, some effort has been put to design the API for stability. However, with limited development resources, and the focus of GROMACS being in high performance simulations, all the APIs are subject to change without notice. With each new release (with possible exception of patch releases), you should expect incompatible API changes.
The header version.h (installed as gromacs/version.h
) provides defines that calling code can use to check the exact (released) version of GROMACS that installed the headers.
This Doxygen documentation only covers part of the API.