Substantial optical dielectric enhancement by volume compression in LiAsSe$_2$

TL;DR

This study predicts a threefold increase in the optical dielectric constant of LiAsSe$_2$ under pressure, due to changes in its 1D chain structure, with implications for energy harvesting applications.

Contribution

It introduces a first-principles prediction of dielectric enhancement in LiAsSe$_2$ under pressure and develops a tight-binding model to explain the underlying physics.

Findings

Optical dielectric constant increases threefold under pressure.

Enhancement is linked to reduced dimerization in 1D chains.

Potential application in light harvesting technologies.

Abstract

Based on first-principles calculations, we predict a substantial increase in the optical dielectric function of LiAsSe$_2$ under pressure. We find that the optical dielectric constant is enhanced threefold under volume compression. This enhancement is mainly due to the dimerization strength reduction of the one-dimensional (1D) As--Se chains in LiAsSe$_2$, which significantly alters the wavefunction phase mismatch between two neighboring chains and changes the transition intensity. By developing a tight-binding model of the interacting 1D chains, the essential features of the low-energy electronic structure of LiAsSe$_2$ are captured. Our findings are important for understanding the fundamental physics of LiAsSe$_2$ and provide a feasible way to enhance the material optical response that can be applied to light harvesting for energy applications.