Lattice-Dynamical Study of theα-βPhase Transition of Quartz: Soft-Mode Behavior and Elastic Anomalies

Abstract
The mechanism of the α-β phase transition of quartz is investigated within the framework of a lattice-dynamical model using the pair-wise potential by Tsuneyuki et al. [Phys. Rev. Lett. 61, 869 (1988)]. The model well describes this effect and shows that the related phenomena (the soft-mode behavior and the negative Poisson ratios) can be mainly attributed to the sensitivity of the potential surface to volume extension.