Ionization potentials of MgO clusters containing a substitutional atom

Abstract

AbstractWith the help of a DFT‐LDA method, computations of the ionization potentials of MgO clusters were made. Starting from (5 × 5 × 5) cubic pieces of a crystal, these clusters were obtained by optimization. In order to study the influence of a substitutional atom, their central atom—either Mg or O—was removed and replaced by other atoms of different valences. These clusters were charged in order to reproduce the density of states of a neutral crystal (full valence band, empty conduction band), then one and two electrons were successively added and removed. When the substitutional atom does not give rise to an impurity level in the bandgap, a linear law of the ionization potentials with respect to the valence of this atom was observed. This law results from the Coulomb interaction between the cluster and the electrons and from the structure of the density of states of the cluster. This allows us to foresee the values of the ionization potentials of an MgO cluster possessing a substitutional atom, according to the valence of this atom. A similar law would probably appear in any cluster of a crystalline insulator. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005