Chapter 9 - Computer Simulations

Abstract

This chapter discusses several simulation methods along with their abbreviated names. The atomistic simulations of materials are broadly classified into two categories: the treatment of structure and dynamics of atoms within the Newtonian dynamics and/or classical statistics, and to study the electronic structure using the quantum mechanics. State-of-the-art simulation techniques are a mixture of the two categories. One of the major applications of the computer simulation is the transformation of graphite into diamond. Graphite transforms at a high pressure. This process serves as a starting point to understand the structural and chemical properties of carbon. From the viewpoint of computer simulation, the transformation is a difficult problem because: the chemical bonds of the carbon atoms change from sp2 to sp3, and the crystal changes from a semi-metal to an insulator. A constant-pressure first-principles molecular dynamics (FPMD) simulation of this transformation has been reported. It was found that the transformation path proceeds through a sliding of graphite planes into an unusual orthorhombic stacking, from which an abrupt collapse and buckling of the planes leads to both cubic and hexagonal forms of the diamond in comparable proportions.