Mechanisms of Phase Transitions in Crystalline Materials

Abstract

The emphasis on structure and function control in material sciences poses new challenges for computer simulations. Intelligent control of materials properties requires a profound knowledge of reaction paths, transformation mechanisms and metastable phases at the atomistic level of detail. Along this line the structure and function of domain boundaries and phase interfaces, defects, dislocations, are of fundamental importance. Especially for bottom-up approaches to device design, insights at the atomic level of detail are mandatory.

The MECMAT project is based on molecular dynamics simulations and targets an understanding of fundamental atomistic aspects for material design, like phase nucleation and phase growth patterns, domain growth and material morphology. The latter are of very difficult experimental accessibility, but are essential for a rational approach to material design.

Silicon, titanium and titanium alloys are principal investigation challenges of the MECMAT projects. The high pressure polymorphism represents a topical system for understanding both covalent bonding reorganization and metallization phenomena. Titanium and titanium alloys are outstanding technological materials with distinct mechanical properties and unusual electronic effects that await a fundamental understanding.

The highly scalable CPMD code (www.cpmd.org) is used in connection with advanced molecular dynamics simulation schemes to elucidate atomistic details in critical snapshots of material formation. The implementation of the CPMD code fully benefits from the use of aggregate memories, needed for the treatment of large systems with first-principles techniques, with a performance speed-up.

The MECMAT project is presented in the framework of the collaboration between the Max-Planck-Institute for the Chemical Physics of Solids Dresden, Germany, and the CNR Institute for Molecular Sciences and Technologies Perugia, Italy.