Existence of the β-tin structure in Sr: First evidence from computational approach

Abstract

Molecular Dynamics (MD) calculation is one of the most powerful theoretical methods widely used to predict and to confirm structural phase transitions. In this work, the MD method has been used to verify phase transition from body-centered cubic (bcc) to β-tin structure, then, to the Cmcm and hexagonal close-packed (hcp) structure, respectively. The transition sequence from previous theoretical works has been confirmed. In this study, Density Functional Theory (DFT), has been used to calculate phonon dispersion to confirm the stability of β-tin and hcp phases. The long time discrepancies in transition sequence between the calculation and the experimental works has been explained by conventional DFT calculation using screened exchange local density approximation (sX-LDA). More importantly, the existence of β-tin structure is finally predicted and the transition nature of Sr has also been revealed.