Phonon transport in perovskite SrTiO3 from first principles

TL;DR

This study uses first-principles methods to analyze phonon transport in SrTiO3, revealing a dominant optical phonon contribution and strong anharmonic effects influencing thermal conductivity.

Contribution

It introduces a first-principles molecular dynamics approach that accurately captures stable phonon behavior in SrTiO3, surpassing traditional perturbation methods.

Findings

Optical phonons contribute over 60% to thermal conductivity.

Strong anharmonic coupling suppresses acoustic phonon transport.

The method reproduces experimentally observed stable phonon dispersion.

Abstract

We investigate phonon transport in perovskite strontium titanate (SrTiO3) which is stable above its phase transition temperature (~105 K) by using first-principles molecular dynamics and anharmonic lattice dynamics. Unlike conventional ground-state-based perturbation methods that give imaginary phonon frequencies, the current calculation reproduces stable phonon dispersion relations observed in experiments. We find the contribution of optical phonons to overall lattice thermal conductivity is larger than 60%, markedly different from the usual picture with dominant contribution from acoustic phonons. The mode- and pseudopotential-dependence analysis suggests the strong attenuation of acoustic phonons transport originated from strong anharmonic coupling with the transversely-polarized ferroelectric modes.