Polymerization in liquid phosphorus: Simulation of a phase transition

We have performed simulations of liquid phases of phosphorus using the molecular-dynamics–density-functional method. Starting from a system of 26 ${\mathrm{P}}_4$ tetrahedra in a simple cubic unit cell of constant volume, we determine radial, angular, and defect distribution functions for the molecular liquid and for polymeric high temperature liquid red P. Comparison with available experimental data and earlier calculations shows that the structures of the amorphous and liquid polymeric phases are very similar. The polymerization of molecular phosphorus is a complex process that may be viewed as a defect-induced chain reaction, in which the elevated temperature and the environment of the tetramers play decisive roles.