Liquid-liquid phase transition of phosphorus (P) was investigated by constant-pressure first-principles MD (FPMD) simiulations [PRL vol.87, 105701 (2001); J.Non-Cryst.Sol. vol.312-314, 22 (2002)].
At low pressures, liquid P forms a molecular liquid consisting of P4 tetrahedral molecules. It is shown by constant-pressure FPMD that compression or heating causes a transition to a polymeric liquid accompanying dissociation of the molecules and large volume contraction.
Structures in the polymeric liquid were investigated in detail, and a Peierls distortion is found around 1GPa. However, further compression causes the reduction of this distortion, and the liquid becomes similar to that of Sb or Bi. This trend is quite similar to that observed in crystalline phases of P [PRB vol.66, 054204 (2002)].
It is also shown that compression or quenching on the polymeric liquid induces crystallization to a distorted simple cubic structure [CPL vol.380, 342(2003)].
