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---

Green/WeakCoupling is a weak-coupling perturbation expansion solver for real materials expressed in Gaussian Bloch orbitals

Installation

Dependencies

Green/WeakCoupling has the following required external dependencies

• HDF5 library version >= 1.10.2
• Message Passing Interface >= 3.1
• Eigen3 library >= 3.4.0
• BLAS

To build Green/WeakCoupling CMake version 3.18 or above is required

PySCF interface requires

• PySCF version >= 2.0
• numba version >= 0.57

Build and Install

The following example will build, test and install Green/WeakCoupling to /path/to/weakcoupling/install/dir directory.

$ git clone https://github.com/Green-Phys/green-mbpt
$ cd green-mbpt
$ mkdir build && cd build
$ cmake -DCMAKE_BUILD_TYPE=Release \
        -DCMAKE_INSTALL_PREFIX=/path/to/weakcoupling/install/dir ..
$ make
$ make test
$ make install

Basic usage

Generate input data

Green/WeakCoupling provides PySCF interface to generate input data and initial starting point through the green-mbtools Python package.

To generate initial mean-field solution and one- and two-body integrals run:

python python/init_data_df.py --a <a.dat> --atom <atom.dat> --nk <nk> --basis <basis specification>

To perform weak-coupling simulations, one have to call mbpt.exe executable located at the installation path in the bin subdirectory. Minimal parameters that are needed to run weak-coupling simulations are following:

• --BETA inverse temperature
• --scf_type type of self-consistent approximation, should be either GW, GF2 or HF
• --grid_file path to a file containing non-uniform grids, program will check three possible locations:
  • current directory or absolute path
  • <installation directory>/share
  • build directory of weak-coupling code

Currently, we provide IR (ir subdirectory) and Chebyshev grids (cheb subdirectory) for nonuniform imaginary time representation.

After succesful completetion results will be written to a file located at --results_file (by default set to sim.h5) To get information about other parameters and their default values call mbpt.exe --help.

Acknowledgements

This work is supported by the National Science Foundation under the award OAC-2310582