Coarse molecular-dynamics analysis of stress-induced structural transitions in crystals

TL;DR

This paper introduces a coarse molecular-dynamics method to analyze stress-induced structural changes in crystals, successfully identifying transition points and free-energy landscapes for bcc-to-hcp transformations under pressure.

Contribution

The study develops a novel CMD approach that uses a carefully chosen coarse variable to map free-energy landscapes and determine transition conditions in crystal structures.

Findings

Identified the critical pressure for bcc-to-hcp transition.

Reconstructed free-energy landscapes of crystal phases.

Demonstrated the method's ability to locate metastable states.

Abstract

We present a coarse molecular-dynamics (CMD) approach for the study of stress-induced structural transformations in crystals at finite temperatures. The method relies on proper choice of a coarse variable (order parameter, observable), which parameterizes the changes in effective free energy during the transformation. Results are reported for bcc-to-hcp lattice transitions under pressure. We explore coarse-variable space to reconstruct an effective free-energy landscape quantifying the relative stability of different metastable basins and locate the onset, at a critical pressure, of the bcc-to-hcp transformation.