Structural and electronic properties of small neutral (MgO)(n) clusters

Ab initio perturbed ion calculations are reported for neutral stoichiometric (MgO)(n) (n less than or equal to 13) clusters. A great number of isomer structures are identified and studied. For the isomers of (MgO)(n) (n less than or equal to 7) clusters, a full geometrical relaxation is considered. Correlation corrections are included for all cluster sizes using the Coulomb-Hartree-Fock model proposed by Clementi [IBM J. Res. Dei. 9, 2 (1965)]. The results obtained compare favorably with the experimental data and other previous theoretical studies. The inclusion of correlation is crucial in order to achieve a good description of these systems. We find a number of important isomers that allow us to interpret the experimental magic numbers without the assumption of structures based on (MgO)(3) subunits. Finally, as an electronic property, the variations in the cluster ionization potential with the cluster size are studied and related to the structural isomer properties.