High‐pressure phases of sulfur: Topological analysis and crystal structure prediction

Abstract

We apply density functional theory (DFT) and evolutionary structure prediction algorithms to study the high‐pressure behavior of sulfur above 100 GPa. Based on DFT calculations, we determined the energetic relations between experimentally observed S‐III, S‐V, and β‐Po structures. S‐V is found to be unstable and transforms to S‐III under optimization. The second order character of transformation from S‐III to β‐Po is theoretically justified and calculations yield a pressure of about 250 GPa. β‐Po structure is not stable in trigonal symmetry below 250 GPa and spontaneously transforms into a monoclinic structure identical to S‐III. The calculations yield pressures of 333 and 460 GPa for the transitions from β‐Po to simple cubic (sc) and from simple cubic to body centered cubic (bcc) structures of sulfur, respectively.