MOLECULAR-DYNAMICS STUDY OF THE ALPHA-STRUCTURAL TO BETA-STRUCTURAL PHASE-TRANSITION OF QUARTZ

The molecular dynamics with a first-principles interatomic potential is used to study the phase transition of quartz from the to 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 structure, atoms in fact hop between the two equivalent 1 and 2 structures by anharmonic motions with a temperature-dependent correlation time. © 1990 The American Physical Society.