Investigation of crystal surfaces with atomic steps by kinetic Monte Carlo technique

In this thesis, the morhological changes on crystal surfaces is investigated by kinetic MonteCarlo simulation technique. The transition rates of surface processes are calculated, the mo-tion of atom or molecules on the surface is followed step-by-step and the transition rates areupdated after each movement. Parameters such as the position of each atom on the lattice, theprobability of motion in a direction, the local particle distribution around them, their energydepending on the bonds they make with their neighbors are recorded dynamically. Further, foreach molecule the accessible states and their probability of occurance are recorded. Knowingthese rates beforehand is necessary to use the Monte Carlo technique. To choose the atoms andthe direction they would move according to respective weight of these rates and the arrangmentof these activities requires a great deal of computer time. High level computer algorithms aredeveloped for the purposes of indexing, searching and classification.Using this method, the movement of step edges on the surface and their correlation func-tions, surface or step roughness and the morphological changes that take place on crystal sur-faces of a certain initial shape as a function of temperature, particle flux and energy barriersare investigated. The dynamical parameters and statistical information related to the surfaceare recorded with high precision (ns scale) and they are later analyzed with various criteria. Itis hard or sometimes impossible to change certain parameters and to anaylze the surface with-out interfering with it in real experiments. With the method used in this thesis, to make thesechanges and to observe their effect is possible. Before using higly sophisticated experimentalapparatus, it is beneficial to consider the predictions of theoretical studies.Key Words: Kinetic Monte Carlo, steps, surface energy, modelling, surface dynamics