Abstract
Two-dimensional YSi2 or ErSi2 layers on Si(111) surface present two surface states in the vicinity of the Fermi level and form a two-dimensional surface electron gas. We have performed density functional theory (DFT) calculations of a realistic one-dimensional nanostructure of YSi2 on Si(111) to study confinement effects of this electron gas. The calculated square modulus of the wave function shows complex modulations related to the quantum interference patterns observed by scanning tunneling microscopy (STM). For each quantised state, the modulation involves at least three components consistent with the scattering of Bloch waves. A Fourier analysis of the real space modulations is used to construct the surface states dispersion curves. They are compared to the direct calculation of the ideal YSi2/Si(111) surface electronic structure and to the E(k) curves deduced from conductance images in STM experiments.