Quantum simulation of structure switching in a molecular system

Abstract

This article presents the results of ab initio quantum simulation of graphite-like structure formation from amorphous carbon. It is devoted to explaining a resistivity switching mechanism in experiments on phase-change memory. In this work, a two-scale molecular dynamics model is used, which consists of Car-Parrinello quantum molecular dynamics (CPMD) and modified Ehrenfest molecular dynamics. The results of simulation point out to the appearance of a layered graphite-like molecular structure at an increase in temperature. These changes in the atomic configuration can be considered as a second-order phase transition in nanostructured material, which leads to threshold resistivity switching. For calculations, the IBM BlueGene/P supercomputer installed at the Faculty of Computational Mathematics and Cybernetics of Moscow State University was used.