Construction of maximally-localized Wannier functions using crystal symmetry

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 sec-ond 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).(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

In this study, two methods for constructing Maximally localized Wannier functions (MLWFs) using crystal symmetry are presented. The first method calculates input matrices for generating MLWFs based on wavefunctions in the irreducible Brillouin zone (IBZ), resulting in reduced computational costs and file sizes. The second method involves calculating symmetry-adapted Wannier functions compatible with the frozen window technique. Examples of Fe, Co3Sn2S2, Cu, and Nb are demonstrated. These methods are implemented in the PW2WANNIER90 code, which interfaces QUANTUM-ESPRESSO with WANNIER90, and the open-source python library, SYMWANNIER.