Неадиабатические переходы атомов и образование зародышей новой фазы в твердых телах

Abstract

A mechanism for the formation of nuclei of a new phase in a solid is proposed, determined by nonadiabatic Landau-Ziner transitions in an open system of nuclei and electrons. Based on the analysis of the equations of nonadiabatic molecular dynamics, two order parameters are identified. The dynamics of the nucleation and growth of the embryo is determined by two related nonlinear parabolic equations for order parameters. The conditions for the formation of stable and unstable embryos are found. It is shown that the formation of the embryo can proceed in an auto-oscillatory mode. The influence of the heating (cooling) rate on the formation of new phase nuclei is considered.