Electronic and optical properties of core-shell InAlN nanorods: a comparative study via LDA, LDA-1/2, mBJ and $G_0W_0$ methods

TL;DR

This study compares the effectiveness of DFT-based methods like LDA, LDA-1/2, and mBJ against the more accurate but costly $G_0W_0$ approach in calculating the electronic and optical properties of core-shell InAlN nanorods.

Contribution

It demonstrates that LDA-1/2 and mBJ can reliably approximate $G_0W_0$ results for nanorod properties at lower computational costs.

Findings

LDA-1/2 and mBJ closely match $G_0W_0$ for band gaps.

Optical properties are well reproduced by LDA-1/2 and mBJ.

Lower computational cost with comparable accuracy.

Abstract

Currently, self-induced InAlN core-shell nanorods enjoy an advanced stage of accumulation of experimental data from their growth and characterization as well as a comprehensive understanding of their formation mechanism by the ab initio modeling based on Synthetic Growth Concept. However, their electronic and optical properties, on which most of their foreseen applications are expected to depend, have not been investigated comprehensively. $G_0W_0$ is currently regarded as a gold-standard methodology with quasi-particle corrections to calculate electronic properties of materials in general. It is also the starting point for higher-order methods that study excitonic effects, such as those based on the Bethe-Salpeter equation. One major drawback of $G_0W_0$, however, is its computational cost, much higher than density-functional theory (DFT). Therefore, in many applications, it is highly desirable to answer the question of how well approaches based on DFT, such as e. g. LDA, LDA-1/2, and mBJ, can approximately reproduce $G_0W_0$ results with respect to the electronic and optical properties. Thus, the purpose of the present paper is to investigate how the DFT-based methodologies LDA, LDA-1/2, and mBJ can be used as tools to approximate $G_0W_0$ in studies of the electronic and optical properties of scaled down models of core-shell InAlN nanorods. For these systems, we observed that band gaps, density of states, dielectric functions, refractive indexes, absorption and reflectance coefficients are reasonably well described by LDA-1/2 and mBJ when compared to $G_0W_0$, however, at a much more favorable computational cost.