High Pressure Phases and the Structural Phase Transition of Selenium

We studied the structural phase transition of Se under high pressure by means of a full-potential linearized-augmented-plane-wave method. We calculated the electronic structure and the total energy at various volumes for the β-Po type rhombohedral and the bcc structure, from which we estimated the transition pressure. It was found that a first-order phase transition appears at a much lower pressure than the observed value with a small volume reduction. The structural properties calculated were discussed and compared with the available experimental data.