Isothermal-isobaric first-principles molecular-dynamics: application to polymorphism in liquids and amorphous materials

The capability of isothermal-isobaric first-principles molecular-dynamics (NPT FPMD) based on the combination of the Car-Parrinello, Andersen, and Nose-Hoover techniques is illustrated by applications to polymorphism in liquids and amorphous materials. Recently, the possible existence of polyamorphic transitions has been extensively investigated in a variety of materials. Here we show NPT FPMD simulations of amorphous-amorphous transitions in silicon and liquid-liquid transitions in phosphorus. Both of these simulations are in excellent agreement with the recent experimental findings. The underlying mechanisms of these polyamorphic transitions have been clarified at an atomistic level.