Structural and electronic properties of small neutral $(\mathrm{MgO}{)}_n$ clusters

Ab initio perturbed ion calculations are reported for neutral stoichiometric $(\mathrm{MgO}{)}_n$ $(n<~13)$ clusters. A great number of isomer structures are identified and studied. For the isomers of $(\mathrm{MgO}{)}_n$ $(n<~7)$ 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. Dev. 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 $(\mathrm{MgO}{)}_3$ 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.