QH-POCC: taming tiling entropy in thermal expansion calculations of disordered materials

TL;DR

This paper introduces QH-POCC, a novel computational method that effectively calculates thermal expansion and related properties in substitutionally disordered materials, addressing a key challenge in materials science.

Contribution

QH-POCC leverages local tile-expansion to enable accurate thermomechanical property calculations for disordered materials within the quasi-harmonic approximation.

Findings

QH-POCC accurately predicts thermal expansion coefficients.

The method's results agree well with experimental data.

It offers a promising tool for studying disordered systems.

Abstract

Disordered materials are attracting considerable attention because of their enhanced properties compared to their ordered analogs, making them particularly suitable for high-temperature applications. The feasibility of incorporating these materials into new devices depends on a variety of thermophysical properties. Among them, thermal expansion is critical to device stability, especially in multi-component systems. Its calculation, however, is quite challenging for materials with substitutional disorder, hindering computational screenings. In this work, we introduce QH-POCC to leverage the local tile-expansion of disorder. This method provides an effective partial partition function to calculate thermomechanical properties of substitutionally disordered compounds in the quasi-harmonic approximation. Two systems, AuCu3 and CdMg3, the latter a candidate for long-period superstructures at low temperature, are used to validate the methodology by comparing the calculated values of the coefficient of thermal expansion and isobaric heat capacity with experiment, demonstrating that QH-POCC is a promising approach to study thermomechanical properties of disordered systems.