2. How to use wan2respack

2.1. Prerequisite

Required packages

Install the following three packages

  1. Quantum Espresso (6.6)

  2. Wannier90 (3.0.0)

  3. RESPACK (20200113)

The versions in parentheses have been tested.

About Python

Python 3.6 or higher version is required.

Python requires tomli library. This tomli library is the standard library for python 3.11. Execute the following command.

pip install tomli

2.2. Structure

wan2respack has the following directory structure

|--CMakeLists.txt
|--LICENSE
|--README.md
|
|--config
|    |
|    |--intel.cmake
|    |--gcc.cmake
|
|--docs
|
|--samples
|    |
|    |--README.md
|    |--Al.fcc.666
|    |--La2CuO4.bct.666
|    |--SrVO3.sc.666
|
|--util
     |
     |--wan2respack

2.3. Installation

wan2respack can be downloaded from the following GitHub page. https://github.com/respack-dev/wan2respack

Users can compile wan2respack using CMake. An example of the installation of wan2respack is as follows

cd $PATH_to_wan2respack
mkdir build
cd build
cmake ../ -DCONFIG=$Type_of_Configure -DCMAKE_INSTALL_PREFIX=$PATH_to_Install
make
make install

where $PATH_to_wan2respack is the path to the wan2respack directory and $PATH_to_Install is the path to the directory for the installation. By replacing $Type_of_Configure with the name of a CMake configure file, the user can specify the compilers they want to use. In the version 1, the following $Type_of_Configure are available.

intel: Intel compiler + MKL
gcc: GCC compiler

The details of the compiler options can be found in the CMake configure files inthe $PATH_to_wan2respack/config directory.

All of the binary files and the Python script are installed to $PATH_to_Install/bin. Their details are as follows:

wan2respack.py

  • Main Python script including two modes: pre-process and core-process. This script requires a configuration toml file as an argument.

gen_mk.x

  • Fortran90 code for calculating k-points mesh for Wannier90. This binary is called by wan2respack_pre.py.

gen_wan.x

  • Fortran90 code for converting the Wannier90 results into the RESPACK Wannier format. This binary is called by wan2respack_core.py.

wan2respack_pre.py

  • Python script for saving the QE results and exporting k-points with gen_mk.x and qe2respack.py.

wan2respack_core.py

  • Python script for preparing files related to Wannier functions in RESPACK format with gen_wan.x and qe2respack.py.

qe2respack.py

  • Python script for generating input files of RESPACK from QE band calculations. This script is originally distributed under GNU GPL ver.3 by open-source software RESPACK ver. 20200113.

init.py

  • Python module in which common functions are defined.

2.4. Basic usage

  1. Perform first principles calculations by QE

  • Only norm-conserving pseudopotentials can work in RESPACK.

  • Perform the calculation at the irreducible k-points.

  1. Run wan2respack.py in pre-process mode

  • Export k-points to be calculated to nscf-input and Wannier90-input.

  1. Generate Wannier functions by QE and Wannier90

  • Use the input files made by the previous step.

  1. Convert Wannier functions to RESPACK format by running wan2respack.py

2.4.1. Prepare input files

Prepare the following files. See Input files for details.

  • QE scf input.

  • QE nscf input.

    • Be sure to use {automatic} to set the k-point.

  • Wannier90 input file.

    • Do not write the k-point block.

  • pw2wannier90 input file.

  • RESPACK input file.

  • configuration toml file.

2.4.2. Run wan2respack

After the calculations at the irreducible k-points,

python wan2respack.py conf.toml -pp

The above command generates new_nscf and new_win files with the k-points list to be calculated.

After the Wannier functions are generated:

python wan2respack.py conf.toml

The dir-wan directory and four files inside this directory are generated.