High-pressure behavior of phosphorus from first principles calculations

High-pressure structural behavior, electronic structure, and vibrational properties of P have been investigated by means of first principles calculations. We perform an ab initio search for the P-IV phase by analyzing the phonon dispersions of the simple cubic (sc) structure as a function of pressure. In particular, we use the dynamical instability of the sc structure above the transition into the simple hexagonal structure to extract a possible candidate structure for P-IV. Additionally, in contrast to general expectations, we show that the body-centered cubic (bcc) P-V phase cannot be the end member of the high-pressure structural sequence of P because it becomes dynamically unstable at high compression. We propose that at ultrahigh pressure above 280 GPa, the bcc structure transforms first to the IM7 structure and then to the hexagonal close-packed structure.