First-principles thermodynamics of transition metals and alloys: W, NiAl, PdTi

TL;DR

This paper uses first-principles calculations to accurately predict the thermal expansion of tungsten, NiAl, and PdTi, demonstrating the effectiveness of the quasiharmonic approximation and anisotropic theory.

Contribution

It introduces a simplified method for calculating anisotropic thermal expansion effects using negative pressure approximation, validated against experimental data.

Findings

Excellent agreement with experimental thermal expansion data.

Validation of anisotropic effects approximation as equivalent to negative pressure.

Effective application of pseudopotential density functional perturbation theory.

Abstract

We apply the pseudopotential density functional perturbation theory approach along with the quasiharmonic approximation to calculate the thermal expansion of tungsten and two important metallic alloys, NiAl and PdTi. We derive the theory for anisotropic crystal structures and test the approximation that the anisotropic effects of thermal expansion are equivalent to negative pressure - this simplifies the calculation enormously for complex structures. Throughout, we find excellent agreement with experimental results.