QUARTZ AMORPHIZATION - A DYNAMICAL INSTABILITY

The results of atomistic simulations based on the Born model of solids show that the crystalline-to-amorphous phase transition in alpha-quar tz is the result of a dynamical instability. This work illustrates the potential of atomistic simulation to identify the atomic mechanisms f or phase transformations. On applying high pressure to alpha-quartz, a n acoustic vibrational mode became unstable, indicating supercell form ation of size 3 x 3 x 1. Further increase in pressure resulted in the collapse of the crystalline structure to an amorphous solid displaying variations in bond length, bond angle and coordination number.