Isotherms for the liquid-gas phase transition in silicon from NPT Monte Carlo simulations

Isotherms for the liquid-gas phase transition in silicon have been calculated using isothermal-isobaric (NPT) Monte Carlo simulations with atom-atom interactions described by the Stillinger-Weber potential. In order to permit high-performance Monte Carlo calculations, a procedure has been developed to compute efficiently changes in the potential energy resulting from one-atom moves; the method is applicable to the Stillinger-Weber potential and other potentials with separable three-body terms. For Stillinger-Weber silicon, the critical temperature, pressure and density have been found to be 7925+/-250 K, 185+/-40 MPa, and 760+/-500 kg/m(3), respectively. From the calculated isotherms, the spinodal line for the liquid-gas phase transition has been estimated.