Absolute and approximate calculations of electron-energy-loss spectroscopy edge thresholds

Systematic studies of binding energies for the electron excitation of core levels for atoms, molecules, and solids have been calculated with various density functional theones. The generalized gradient approximation provides the most accurate description of the absolute binding energies when spin polarization is included. Relative core level shifts can be determined to within 0.5 eV without spin polarization. Core level shifts can be predicted from ground-state eigenvalue differences only when comparing environments of similar electronegativity. Such is the case for the O K edge, but not the Si L edge at Si/SiO2 interfaces in nanotransistors.