RESPACK: An ab initio tool for derivation of effective low-energy model of material

RESPACK is a first-principles calculation software for evaluating the interaction parameters of materials and is able to calculate maximally localized Wannier functions, response functions based on the random phase approximation and related optical properties, and frequency-dependent electronic interaction parameters. RESPACK receives its input data from a band-calculation code using norm-conserving pseudopotentials with plane-wave basis sets. Automatic generation scripts that convert the band-structure results to the RESPACK inputs are prepared for xTAPP and Quantum ESPRESSO. An input file for specifying the RESPACK calculation conditions is designed pursuing simplicity and is given in the Fortran namelist format. RESPACK supports hybrid parallelization using OpenMP and MPI and can treat large systems including a few hundred atoms in the calculation cell. Program summary: Program Title: RESPACK CPC Library link to program files: https://dx.doi.org/10.17632/3cxb7474nj.1 Developer's repository link: https://sites.google.com/view/kazuma7k6r Licensing provisions: GNU General Public Licence v3.0 Programming language: FORTRAN, PYTHON External routines: LAPACK, BLAS, MPI Nature of problem: Ab initio calculations for maximally localized Wannier function, response function with random-phase approximation, and matrix-element evaluations of frequency-dependent screened direct and exchange interactions. With this code, an effective low-energy model of materials is derived from first principles. Solution method: Our method is based on ab initio many-body perturbation calculation and the maximally localized Wannier function calculation. The program employs the plane-wave basis set, and evaluations of matrix elements are performed with the fast Fourier transformation. The generalized tetrahedron method is used for the Brillouin Zone integral. Additional comments including restrictions and unusual features: RESPACK supports xTAPP and Quantum ESPRESSO packages, and automatic generation scripts for converting the band-calculation results to the RESPACK inputs are prepared for these software. The current RESPACK only supports band-calculation codes using norm-conserving pseudopotentials with plane-wave basis sets. RESPACK supports hybrid parallelization using OpenMP and MPI to treat large systems in which a few hundred atoms are contained in unit cell.