Atomistic Discussion of Metastable States from Viewpoints of MD Simulations and Experiments

Comprehension of metastable states in the course of phase transition, decomposition, melting, crystallization is one of significant subjects in the solid state earth dynamics. The following categories in the electronic, atomic or lattice transformation must be taken into account for the metastable phenomena of the above structure changes; (A) kinetic factor such as nucleation rate, growth rate, rate of compression and depression, heating rate and reaction duration, (B) environmental physical and thermodynamical parameters. In addition to experimental approaches to clarify metastable states, atomistic computer simulations offer informations of the precursor phenomena of structure changes under the desired physical conditions. For an example of these calculations, present MD calculation simulates the mechanism of pressure-induced amorphization of GeO2 and its polymorphic phase transformation of post-rutile phase under hydrostatic and nonhydrostatic conditions.