Installation

Dependencies

Core

The following packages are required for the core functionality of the software:

Package	Purpose
numpy	Array computing
scipy	Sparse matrices, linear algebra, optimization
numba	JIT compilation for ED basis construction
h5py	HDF5 file I/O

Optionally, GEM provide MPI parallelization support for k-points summations and for the internal solver SimpleED. To enable MPI support, the following packages are required:

Package	Purpose
mpi4py	MPI support for parallelization

Solvers

GEM comes with a simple internal exact diagonlization solver and with interfaces to external solvers If you want to use an external solver then install the packages corresponding to the solvers you intend to use. When using a solver different from SimpleED please make sure to cite the appropriate references along the GEM one.

Solver	Extra packages required
SimpleED	(none)

Testing

Tests run with make test (or ctest) and need no extra packages. The serial tests can also be run with pytest test/python.

Documentation

The following python packages are required to build the HTML documentation. To enable building the documentation locally pass the appropriate flag to cmake (cmake -DBuild_Documentation=ON):

Package	Purpose
sphinx-rtd-theme	Read the Docs HTML theme
nbsphinx	Jupyter notebook support
myst-parser	Markdown source file support
sphinx-autorun	Executable code blocks in docs
numpydoc	NumPy-style docstring parser
linkify-it-py	Auto-linking of bare URLs
matplotlib	Plots in documentation via plot directive
sphinxcontrib-bibtex	BibTeX citations and reference list

Installation Steps

1. Clone the repository:

   git clone https://github.com/triqs/gem.git
   

2. Create a build directory and run CMake:

   mkdir gem.build && cd gem.build
   cmake ../gem
   

3. Build and install:

   make
   make test # or 'ctest -j ${NPROC}' to run tests in parallel when MPI is enabled
   make install
   

Custom CMake Options

The build can be configured with the following CMake options:

cmake ../gem -DOPTION1=value1 -DOPTION2=value2 ...

Option	Syntax
Specify a custom installation prefix	-DCMAKE_INSTALL_PREFIX=<path>
Disable tests (not recommended)	-DBuild_Tests=OFF/ON
Build the documentation	-DBuild_Documentation=OFF/ON
Path to sphinx	-DSPHINXBUILD_EXECUTABLE=<path>
Python interpreter to use	-DPython3_EXECUTABLE=<path>

Environment setup

GEM provides a small script (gemvars.sh) to load its installation into your environment variables. Please source it with the proper replacement of (INSTALL_PREFIX):

source $INSTALL_PREFIX/share/gem/gemvars.sh

To automate this process, please add this line to your ~/.bash_profile (or ~/.zprofile).