Calculated Structural Phase Transitions in the Alkaline Earth Metals

Abstract

The local-density approximation and the linear muffin-tin orbital method have been used within the atomic-sphere approximation to calculate structural energy differences for all the alkaline earth metals at zero temperature. At ordinary pressure the calculations predict the crystal structure sequence hcp\ensuremath{\rightarrow}fcc\ensuremath{\rightarrow}bcc as a function of atomic number. As a function of pressure they predict the structure sequence fcc\ensuremath{\rightarrow}bcc\ensuremath{\rightarrow}hcp. The structural transitions and the onset of superconductivity under pressure are correlated with the $d$ occupation number.