Ab initio investigation of lattice dynamics of fluoride scheelite LiYF4

TL;DR

This paper uses first-principles calculations to study the phonon dynamics of LiYF4, revealing mode inversions and analyzing phonon density of states, with results aligning well with experimental data.

Contribution

It provides a detailed ab initio analysis of lattice vibrations in LiYF4, including mode inversions and phonon density of states, enhancing understanding of its vibrational properties.

Findings

Agreement between experimental and calculated phonon modes

Inversion of Raman active modes compared to experiments

Presence of multiple mode inversions above 360 cm-1

Abstract

We report on the phonon dynamics of LiYF4 obtained by direct method using first principle calculations. The agreement between experimental and calculated modes is satisfactory. An inversion between two Raman active modes is noticed compared to inelastic neutron scattering and Raman measurements. The atomic displacements corresponding to these modes are discussed. Multiple inversions between Raman and infrared active groups are present above 360 cm-1. The total and partial phonon density of state is also calculated and analyzed.