Molecular Dynamics Simulation of Displacive Phase Transitions

Displacive phase transitions have been extensively modelled by the 4 model. In this project, this model is applied to a system with a scalar displacement at each ‘atom’ in a three-dimensional lattice. The behaviour of the system is simulated using molecular dynamics techniques on a massively parallel computer. The code is tested to confirm that the simulation is behaving correctly and is sufficiently accurate. Landau theory predicts the variation of average displacement with temperature, which is compared to that observed in these simulations. The simulations are also used to try to measure one of the parameters in the Landau theory, in two different ways. The results of applying Landau theory to the system are discussed.