Lattice dynamics and thermophysical properties of h.c.p. Re and Tc from the quasi-harmonic approximation

TL;DR

This paper uses first-principles calculations within the quasi-harmonic approximation to analyze phonon frequencies and thermophysical properties of h.c.p. Re and Tc, comparing anisotropic and simplified models with experimental data.

Contribution

It provides a detailed first-principles study of phonon and thermophysical properties of Re and Tc, including anisotropic effects, within the quasi-harmonic approximation.

Findings

Good agreement with experimental data

Differences between anisotropic and simplified models analyzed

Temperature-dependent lattice parameters and thermal expansion characterized

Abstract

We report first-principles phonon frequencies and anharmonic thermodynamic properties of h.c.p. Re and Tc calculated within the quasi-harmonic approximation, including Gr\"uneisen parameters, temperature-dependent lattice parameters, thermal expansion, and isobaric heat capacity. We discuss the differences between a full treatment of anisotropy and a simplified approach with a constant $c/a$ ratio. The results are systematically compared with the available experimental data and an overall satisfactory agreement is obtained.