Theoretical and computational study of time dependent scattering on a 2D surface

Abstract

THEORETICAL AND COMPUTATIONAL STUDY OF TIME DEPENDENT SCATTERING ON A 2D SURFACE by Michael Sohn Dr. Bernard Zygelman, Examination Committee Chair Professor of Physics University of Nevada, Las Vegas The quantum mechanical treatment of the elastic scattring of atoms from a crystal surface provides valuable information, such as surface properties and gas-surface interaction potentials. However, since it is based on the stationary state solution, it does not provide the details of the scattering process in the neighborhood of the surface, especially when atoms are physically adsorbed. In this thesis, the time evolution of the scattering process is treated in 2D with a model potential, V (x, z) = −|g|δ(z) + λδ(z) cos(2πx/a), using the Gaussian wave packet approach. The focus is on the case where the Gaussian wave packet makes a transition into a selective adsorption state because it can provide information on the probability density of selectively adsorbed particles as well as the details of the scattering process in the neighborhood of the surface. The obtained Gaussian wave packet solution shows a transition into a selective adsorption state. However, the probability density of selectively adsorbed particles cannot be accurately determined because the Gaussian wave packet constructed from the Born approximate timeindependent wave function does not conserve the total probability density.