# Quasiparticle self-consistent $GW$ band structures of Mg-IV-N$_2$ compounds: the role of semicore $d$ states

## TL;DR

This study improves quasiparticle self-consistent $GW$ calculations of Mg-IV-N$_2$ compounds by including semicore states, revealing significant band gap reductions and implications for optoelectronic applications.

## Contribution

It introduces the inclusion of semicore $d$ states in $GW$ calculations for Mg-IV-N$_2$ compounds, enhancing accuracy of band gap predictions.

## Key findings

- Semicore $d$ states significantly reduce the band gap.
- MgSnN$_2$ has a band gap in the visible green spectrum.
- Materials stability and electronic properties are characterized.

## Abstract

We present improved band structure calculations of the Mg-IV-N$_2$ compounds in the quasiparticle self-consistent $GW$ approximation. Compared to previous calculations (Phys. Rev. B 94, 125201 (2016)) we here include the effects of the Ge-3$d$ and Sn-4$d$ semicore states and find that these tend to reduce the band gap significantly. This places the band gap of MgSnN$_2$ in the difficult to reach green region of the visible spectrum. The stability of the materials with respect to competing binary compounds is also evaluated and details of the valence band maximum manifold splitting and effective masses are provided.