Molecular-dynamics study of the<i>α</i>to<i>β</i>structural phase transition of quartz

Abstract

The molecular dynamics with a first-principles interatomic potential is used to study the phase transition of quartz from the \ensuremath{\alpha} to \ensuremath{\beta} phase. The phase transition, successfully reproduced at about 850 K, is shown to have a peculiar dynamical character in that, although the probability distribution for atomic positions mimics, when averaged over a long time, a displacive shift to the \ensuremath{\beta} structure, atoms in fact hop between the two equivalent ${\ensuremath{\alpha}}_{1}$ and ${\ensuremath{\alpha}}_{2}$ structures by anharmonic motions with a temperature-dependent correlation time.