Acetylene adsorption onto Si(1Â 0Â 0): a study of adsorption dynamics and of surface steps

In this study the interactions of organic molecules with the silicon surface are considered. The purpose is either to achieve some methodological advantages in a time-dependent quantum mechanical representation of adsorption or to describe effects of the surface structure so far absent from the literature. The acetylene molecule is used as a show-case example and the study is divided into two parts. The first part deals with the dynamical aspects of adsorption. A time-dependent quantum mechanical method with a semi-empirical Hamiltonian is presented and its results are compared with the ones in the literature. The second part analyzes the functionality of a surface containing steps. In these calculations acetylene is deposited onto the steps of a silicon surface vicinal to (1 0 0) and the optimal configuration of the system is evaluated under stationary conditions from the minimization of the total energy. The simulation method is based on two Hamiltonians, i.e. semiempirical Hartree-Fock and density functional, and uses a cluster to model the exposed surface.