Constant pressure reactive molecular dynamics simulations of phase transitions under pressure: The graphite to diamond conversion revisited

We have introduced a new technique for constant-pressure molecular dynamics by combining the idea behind the Parrinello-Rahman scheme and the method by Iannuzzi, Laio and Parrinello [Phys. Rev. Lett. 90, 238302 (2003)], recently devised to deal with rare events. The new scheme is suitably devised to describe solid-solid phase transitions for which the primary order parameter is not the cell shape, but some internal structural coordinate. The method has been demonstrated by simulating the conversion of graphite into diamond at high pressure within a tight-binding model.