Solving a problem with a single parameter: A smooth bcc to fcc phase transition for metallic lithium

TL;DR

This paper uses density functional calculations to show that metallic lithium's bcc and fcc phases are nearly degenerate with a small activation barrier, explaining phase stability at different temperatures.

Contribution

It demonstrates that the bcc phase of lithium is quasi-degenerate with the fcc phase and clarifies the phase stability controversy using a computational approach.

Findings

bcc and fcc phases are nearly degenerate with a small activation barrier

bcc phase becomes dominant at higher temperatures

resolves long-standing controversy about lithium phases

Abstract

Density functional calculations for metallic lithium along a cuboidal bcc-to-fcc transformation path demonstrate that the bcc phase is quasi-degenerate with the fcc phase with a very small activation barrier of 0.1~kJ/mol, but becomes the dominant phase at higher temperatures in accordance with Landau theory. This resolves the long-standing controversy about the two phases for lithium.