Calculation of surface core-level shifts within complete screening: Problems with pseudohydrogenated slabs

Abstract

By considering GaAs(110) and $\text{Si}(100)(2\ifmmode\times\else\texttimes\fi{}1)$ surfaces, it is shown that the use of the pseudohydrogen atoms to saturate the dangling bonds at one side of the slab modeling a free surface can lead to distorted surface core-level shifts within the complete screening picture. The effect is linked to the polarization of the slab and to the change in the bulklike electronic structure close to pseudohydrogenated part of the slab. It is demonstrated that these problems can be avoided if the pseudohydrogenated slab is large enough and the bulk reference layer is properly chosen. One easy way to control these errors is to monitor the planar-averaged potential energy curve of the slab.