Dielectric function of the Si(113)3x2ADI surface from ab-initio methods
  We have investigated the imaginary part of the dielectric function Im(epsilon) of the (113) 3x2 ADI reconstructed surface of silicon. The calculations have been performed for a periodic slab within the plane-wave pseudopotential approach to the density-functional theory. The three diagonal components of Im(epsilon) have been derived from the momentum matrix elements within the independent particle random phase approximation (IPRPA). In this article, the importance of the k-point convergence is figured out by inspecting k-point resolved spectra. 
Katalin Gaal-Nagy and Giovanni Onida