Comparative analysis for the behavior of beryllium and magnesium crystals at ultrahigh pressures

TL;DR

This study uses ab initio calculations to analyze the structural and electronic behavior of beryllium and magnesium crystals under ultrahigh pressures, revealing phase stability and electronic changes such as band gap formation.

Contribution

It provides new insights into the phase stability and electronic structure of Be and Mg at multi-terapascal pressures, including the stability of Be's BCC phase and electronic transformations in Mg.

Findings

Mg undergoes multiple structural transformations reducing packing factor

Be's BCC phase remains stable under ultrahigh pressures

A narrow band gap appears in Mg above 2.5 TPa

Abstract

The paper presents ab initio results on the structural phase stability of beryllium and magnesium crystals under high and ultrahigh pressures (multi-terapascal regime). Magnesium is shown to undergo a number of structural transformations which markedly reduce the crystal packing factor. As for beryllium, its high-pressure body-centered cubic phase remains stable even under ultrahigh pressures. Changes in the electronic structure of Be and Mg crystals under compression are analyzed and some interesting effects are revealed. Specifically, a narrow band gap appears in the electronic structure of magnesium under pressures above 2.5 TPa. For the metals of interest, PT-diagrams are constructed and compared with available experimental and theoretical results from other investigations.