Quasiparticle calculations of surface core-level shifts

Abstract

We report quasiparticle calculations of chemical shifts of core levels at clean and adsorbate-covered Si surfaces. Core-state excitation energies are given as poles of the electronic one-particle Green's function of the many-electron system. To calculate the Green's function, we employ the $\mathrm{GW}$ approximation for evaluating the necessary electronic self-energy operator. The core states whose shifts are addressed in this work are explicitly included in the valence shell. We present results for three different surfaces. For the As:Si(111)-(1$\ifmmode\times\else\texttimes\fi{}$1) and H:Si(111)-(1$\ifmmode\times\else\texttimes\fi{}$1) surfaces, we obtain core-level shifts in good agreement with experimental data. For the clean Si(001) surface a high sensitivity of the chemical shifts on the actual dimer structure of the surface is observed.