Photoelasticity of crystalline and amorphous silica from first principles

TL;DR

This study uses first-principles density-functional perturbation theory to compute and analyze the photoelastic tensors of various crystalline and amorphous silica phases, providing insights into their optical properties under different conditions.

Contribution

It presents the first-principles calculation of photoelastic tensors for multiple silica phases, including amorphous silica, and develops a phenomenological model based on ab-initio data.

Findings

Good agreement with experimental data for crystalline silica

Developed a phenomenological model for silica photoelasticity

Validated computational approach on silicon and MgO

Abstract

Based on density-functional perturbation theory we have computed from first principles the photoelastic tensor of few crystalline phases of silica at normal conditions and high pressure (quartz, $\alpha$-cristobalite, $\beta$-cristobalite) and of models of amorphous silica (containig up to 162 atoms), obtained by quenching from the melt in combined classical and Car-Parrinello molecular dynamics simulations. The computational framework has also been checked on the photoelastic tensor of crystalline silicon and MgO as prototypes of covalent and ionic systems. The agreement with available experimental data is good. A phenomenological model suitable to describe the photoelastic properties of different silica polymorphs is devised by fitting on the ab-initio data.