First-principles study of vibrational and dielectric properties of {\beta}-Si3N4

TL;DR

This study uses first-principles calculations to analyze the vibrational and dielectric properties of {eta}-Si3N4, providing detailed theoretical insights that align well with experimental data.

Contribution

It offers a comprehensive first-principles analysis of {eta}-Si3N4's vibrational and dielectric properties, including phonon modes and dielectric constants, with results matching experimental findings.

Findings

Optical-mode frequencies and LO-TO splittings are accurately predicted.

The static dielectric tensor is decomposed into contributions from phonon modes.

High-frequency phonon modes significantly influence the dielectric constant.

Abstract

First-principles calculations have been conducted to study the structural, vibrational and dielectric properties of {\beta}-Si3N4. Calculations of the zone-center optical-mode frequencies (including LO-TO splittings), Born effective charge tensors for each atom, dielectric constants, using density functional perturbation theory, are reported. The fully relaxed structural parameters are found to be in good agreement with experimental data. All optic modes are identified and agreement of theory with experiment is excellent. The static dielectric tensor is decomposed into contributions arising from individual infrared-active phonon modes. It is found that high-frequency modes mainly contribute to the lattice dielectric constant.