A phonon irreducible representations calculator

TL;DR

This paper introduces PhononIrep, a new software tool that calculates phonon band irreducible representations at the first-principles level, enabling advanced phonon property analysis and predicting novel phenomena like Dirac points.

Contribution

The paper presents PhononIrep, a novel package that extends existing tools to compute phonon irreducible representations for arbitrary k-points from first-principles data.

Findings

Predicted the existence of cubic crossing Dirac points in certain crystal phonon systems.

Enabled detailed symmetry analysis of phonon band structures.

Facilitated future phonon research with a new computational tool.

Abstract

The irreducible representation of band structure is important for physical properties. Based on phonopy and recently developed SpaceGroupIrep package, we developed a package PhononIrep, which can get the band irreducible representation for arbitrary $\boldsymbol{k}$ point at first-principles level. As an application, we for the first time predict the cubic crossing Dirac point can exist in conventional crystal phonon systems X$_3$Y (X=Ti, Nb, Ta, Y=Au, Sb). We hope this package will facilitate phonon research in the future.