Selection of strain and fitting schemes for calculating higher-order elastic constants

TL;DR

This paper proposes improved criteria for selecting strain and fitting schemes to calculate higher-order elastic constants more efficiently and accurately, demonstrated through third-order elastic constants of diamond, resolving previous experimental and theoretical discrepancies.

Contribution

It introduces new selection criteria for strain and fitting schemes that enhance the efficiency, robustness, and accuracy of calculating higher-order elastic constants.

Findings

The method is 3-5 times faster than existing approaches.

The strain range for accurate TOECs is expanded.

Provides recommended TOECs values for diamond.

Abstract

Criteria of selecting strain and fitting schemes are proposed for the calculation of higher-order elastic constants more efficiently, robustly and accurately. As demonstrated by the third-order elastic constants (TOECs) of diamond, the proposed method is 3-5 times faster than existing methods, and the range of strain for getting correct TOECs is expanded. In addition, our result provides an evidence for the inaccuracy of some previous experiments caused by higher-order effect, and the difference among experiments and several different theoretical methods is resolved. Finally, we give the recommend TOECs values for diamond.