Core excitations in MgO: a DFT study with cluster models

The time dependent density functional theory has been employed to calculate the absorption spectra relative to core excitation of Mg 1s, Mg 2p and O 1s orbitals of solid MgO. Cluster models of various size and shape are considered, embedded within an array of point charges to simulate the Madelung potential. Comparison with experimental data and previous theoretical calculations allows a precise assessment of the performances of the present method, which is competitive and promising for further application to more complex systems, like transition metal oxides.