Minimal d-Band Model for the Optical Susceptibility of Non-Centrosymmetric Monolayer Transition Metal Dichalcogenides

TL;DR

This paper introduces a minimal d-band model to efficiently calculate the optical susceptibility of non-centrosymmetric monolayer TMDCs, capturing essential physics with reduced computational complexity.

Contribution

It presents a simplified d-band model that accurately reproduces first-principles optical response calculations for TMDC monolayers, enabling easier inclusion of many-body effects and SOC.

Findings

Model reproduces first-principles results

Simplifies calculations of optical susceptibilities

Facilitates inclusion of many-body effects

Abstract

The optical response of two-dimensional (2D) materials has been customarily calculated ab initio using plane waves and without separating the most important orbitals contributions. In the family of transition metal dichalcogenides (TMDC) monolayers lacking inversion symmetry, we take advantage of the mostly d-orbital content of the Bloch bands around the semiconductor gap to reduce the calculation of the linear and quadratic optical susceptibilities to a very minimal model. Such a simple approach reproduces well first principles calculations and could be the starting point for the inclusion of many-body effects and spin-orbit coupling (SOC) in TMDCs with only a few energy bands in a numerically inexpensive way.