Construction of maximally-localized Wannier functions using crystal symmetry

Abstract

In this study, we show two methods concerning constructions of Maximally localized Wannier functions (MLWFs) using crystal symmetry. The first one is to compute input matrices for generating MLWFs only using wavefunctions in the irreducible Brillouin zone (IBZ). This approach reduces the computational costs and the size of intermediate files in proportion to the number of k points in the IBZ. The second method is to calculate the symmetry-adapted Wannier functions that are compatible with so-called frozen window technique, that is, the procedure to disentangle band structures by forcing Bloch states in a certain energy range to be included. We demonstrate how these work in the case of Fe, Co3Sn2S2, Cu, and Nb. These methods are implemented in PW2WANNIER90 code, which interfaces Quantum-ESPRESSO with the Wannier90, and the open-source python library, SymWannier. The code supports both unitary and anti-unitary symmetry operations as well as nonsymmorphic group operations, spin-orbit couplings, and ultrasoft/PAW pseudopotentials. All of these codes are available on GitHub (https://github.com/wannier-utils-dev/symWannier).