Abstract
Bloch wavefunctions in solids form a representation of crystalline symmetries. Recent studies revealed that symmetry representations in band structure can be used to diagnose the topological properties of weakly interacting materials. In this work, we introduce an open-source program qeirreps that computes the representation characters in a band structure based on the output file of Quantum ESPRESSO. Our program also calculates the Z4 index, i.e., the sum of inversion parities at all time-reversal invariant momenta, for materials with inversion symmetry. When combined with the symmetry indicator method, this program can be used to explore new topological materials. Program summaryProgram title: qeirrepsCPC Library link to program files:https://doi.org/10.17632/dfgw6wgvmt.1Licensing provisions: GNU General Public Licence 3.0Programming language: Fortran 90External routines/libraries:•BLAS (http://www/netlib.org/blas)•LAPACK (http://www.netlib.org/lapack)Nature of problem: Irreducible representations of Bloch wavefunctionsSolution method: Linear algebra calculation for Bloch wavefunctions
Highlights
One of the main goals in condensed matter physics is to predict the properties of materials of our interest by solving the Schrodinger equation
These methods diagnose the topology of the target material by comparing its irreducible representations with those of atomic insulators
The choice of g’s is not unique, and in our program, they are automatically selected by Quantum ESPRESSO based on the input file
Summary
One of the main goals in condensed matter physics is to predict the properties of materials of our interest by solving the Schrodinger equation. The theory of symmetry indicators has been extended to magnetic space groups [59] and superconductors [60, 61, 62, 63, 64, 65], and further investigation of topological magnetic materials and superconductors is awaiting us Having in mind these applications, it is important to make it possible to automatically compute irreducible representations of Bloch wavefunctions by using DFT. We develop an open-source code, named qeirreps, that works for symmorphic and non-symmorphic space groups This would allow everyone to compute the band structure and determine the irreducible representations by themselves, and when combined with the method of symmetry-indicator, would help our search of novel topological materials like topological superconductors as partially demonstrated in Ref. We always consider the little group Gk
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