Molecular Cluster Calculations of the Electronic Structure of the (111) Surface of CaF2
Molecular cluster calculations within the Local Density Approximation have been performed to analyze the electronic structure of stoichiometric and different non-stoichiometric (111) surfaces of CaF2. The effect of the surrounding crystal ions, i.e. the long range electrostatic potential, have been included by a Fourier summation. Calculations for clusters representing the bulk and stoichiometric surfaces give similar results while calculations for non-stoichiometric surfaces show the existence of occupied surface states in the upper half of the bandgap. Existence of these types of occupied surface states are supported by experimental EELS studies on CaF2 as well as by observation of laser induced emission of ions and electrons from surfaces of BaF2.
KeywordsLocal Density Approximation Ionic Crystal Molecular Cluster Surface Cluster Swedish Natural Science Research Council
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