Revisiting the third-order elastic constants of diamond: the higher-order effect

TL;DR

This paper investigates the impact of higher-order elastic effects on diamond's third-order elastic constants using density functional theory, revealing significant effects on shock wave experiments and improving convergence of theoretical predictions.

Contribution

It introduces a higher-order elastic response analysis up to fifth order, enhancing the accuracy of TOECs calculations for diamond.

Findings

Higher-order effects are significant in shock wave experiments.

Including up to fifth order improves convergence of TOECs.

The study resolves discrepancies among different theoretical and experimental methods.

Abstract

In this letter, we study the higher-order effect on the third-order elastic constants (TOECs) of diamond using longitudinal stress-uniaxial strain (LSUS) approach based on density functional theory. The result shows that the higher-order effect on TOECs is not negligible in the shock wave experiments and similar calculations. By taking the higher-order elastic response (up to fifth order) into consideration, the convergence of TOECs against maximum stain gets improved significantly and resolves the discrepancy of several different theoretical methods and experiments.