THEORY OF STRUCTURAL, ELECTRONIC, VIBRATIONAL, AND SUPERCONDUCTING PROPERTIES OF HIGH-PRESSURE PHASES OF SULFUR

Pseudopotential ab initio calculations are performed for three high-pressure phases of sulfur (bco, beta-Po, and bcc). These calculations yield a value of around 550 GPa for the transition pressure of the beta-Po to bcc transformation; however, we do not reproduce the reported bco to beta-Po phase transition. Ab initio calculations of the phonon spectrum and the electron-phonon interaction for the bcc phase of sulfur are also done using the frozen phonon method. The results predict that the bcc phase of sulfur is a metal with very low resistivity and a superconducting transition temperature of 15 K.