Ab initio optical properties of Si(100)

We compute the linear optical properties of different reconstructions of the clean and hydrogenated Si(100) surface within DFT-LDA, using norm-conserving pseudopotentials. The equilibrium atomic geometries of the surfaces, determined from self-consistent total-energy calculations within the Car-Parrinello scheme, strongly influence reflectance anisotropy spectra, showing differences between the p(2 x 2) and c(4 x 2) reconstructions. The differential reflectivity spectrum for the c(4x2) reconstruction shows a positive peak at (h) over bar omega<1 eV, in agreement with experimental results. [S0163-1829(99)03928-4].