SPADExp: A photoemission angular distribution simulator directly linked to first-principles calculations

TL;DR

SPADExp is a software tool that directly links first-principles calculations to simulate photoemission angular distributions in ARPES, enabling analysis of complex materials without tight-binding models.

Contribution

It introduces a novel software that integrates first-principles outputs for PAD calculations, allowing large system analysis and comparison with experimental ARPES data.

Findings

Successfully reproduces characteristic ARPES intensity patterns in graphene and graphite.

Accurately simulates 12-fold symmetric spectra in twisted bilayer graphene.

Shows good agreement with experimental data on topological insulator Bi2Se3.

Abstract

We develop a software package SPADExp (simulator of photoemission angular distribution for experiments) to calculate the photoemission angular distribution (PAD), which is the momentum dependence of spectrum intensity in angle-resolved photoemission spectroscopy (ARPES). The software can directly load the output of the first-principles software package OpenMX, so users do not need to construct tight-binding models as previous studies did for PAD calculations. As a result, we can calculate the PADs of large systems such as quasicrystals and slab systems. We calculate the PADs of sublattice systems (graphene and graphite) to reproduce characteristic intensity distributions, which ARPES has experimentally observed. After that, we investigate twisted bilayer graphene, a quasicrystal showing 12-fold rotational symmetric spectra in ARPES, and the surface states of the topological insulator $\mathrm{Bi}_2\mathrm{Se}_3$. Our calculations show good agreement with previous ARPES measurements, showing the correctness of our calculation software and further potential to investigate the photoemission spectra of novel quantum materials.