Self-consistent-field calculations of core excited states

摘要

The accuracy of core excitation energies and core electron binding energies computed within a self-consistent-field framework is assessed. The variational collapse of the core excited state isprevented by maintaining a singly occupied core orbital using an overlap criterion called themaximum overlap method. When applied to a wide range of small organic molecules, the resultingcore excitation energies are not systematically underestimated as observed in time-dependentdensity functional theory and agree well with experiment. The accuracy of this approach for coreexcited states is illustrated by the calculation of the pre-edge features in x-ray absorption spectra ofplastocyanin, which shows that accurate results can be achieved with Δself-consistent-fieldcalculations when used in conjunction with uncontracted basis functions.