IRSSG: An Open-Source Software Package for Spin Space Groups

TL;DR

IRSSG is an open-source software tool that analyzes magnetic systems using spin space groups within the DFT framework, aiding research in magnetic topology and excitations.

Contribution

The paper introduces IRSSG, a new software package that identifies spin space group operations and characterizes magnetic energy bands from DFT wavefunctions.

Findings

Successfully identifies all SSG operations for given magnetic systems.

Generates SSG character tables and assigns irreducible corepresentations.

Facilitates research in magnons, altermagnetism, and magnetic topology.

Abstract

We present an open-source software package IRSSG for investigating magnetic systems with spin space groups (SSGs). The package works within the density functional theory (DFT) framework and requires wavefunctions from DFT codes, such as VASP, Quantum ESPRESSO, as well as any other code that has an interface to Wannier90. We introduce a set of compact SSG international symbols by combining non-crystallographic point groups with the 230 crystallographic space groups. The program first identifies all SSG operations and determines the SSG international symbol for a given magnetic system. It then generates the SSG character tables of little groups at any $k$ point. Finally, it computes the traces of matrix representations of SSG operations and assigns irreducible corepresentation labels to magnetic energy bands. The program is not only timely but also essential for advancing research on the study of magnons, altermagnetism, magnetic topology, and novel high-degeneracy excitations in SSG systems.