Chapter 5 - Theoretical studies

Abstract

This chapter describes two powerful approaches—Monte Carlo (MC) and molecular dynamics (MD)—to modeling the structure of glasses. In the MC simulation of a glass, a random assembly of a fairly large number of constituent particles of a glass is determined by the chemical composition. The positions can be chosen randomly to be filled into a volume fixed based on known experimental density of the glass. The number of particles is generally chosen on the basis of the available computational time. MC simulation is good for calculating energies of the metastable equilibrium configuration in glass. But to obtain dynamical information it is better to employ MD simulation. In MD simulations, the emphasis is on the motion of the particles. Classical equations of motion of particles are solved and evolution of the system with time is examined in the chapter. The procedure therefore provides a complete history of each particle and enables extracting the dynamical information. A chosen number of particles are assembled in a box that is generally of cubical shape. The number of particles should be preferably a few hundred because of the problem of termination errors particularly when Coulombic potentials are used.