A density functional theory and electron momentum spectroscopy study into the complete valence electronic structure of cubane

A study of the electronic structure of the complete valence shell of cubane is reported. Results from our many-body Green's function calculation, to t he third-order algebraic diagrammatic construction (ADC(3)) level, for the binding energies and spectroscopic factors of the respective valence orbita ls of cubane are presented. Binding-energy spectra were measured in the ene rgy regime 6-35 eV over a range of different target electron momenta, so th at momentum distributions (MDs) could be determined for each orbital. The c orresponding theoretical MDs were calculated using a plane wave impulse app roximation (PWIA) model for the reaction mechanism and density functional t heory (DFT) for the wave function. Seven basis sets, at the local density a pproximation (LDA) level and, additionally, incorporating nonlocal correlat ion functional corrections, were studied. The sensitivity of the level of a greement between the experimental and theoretical MDs to the nonlocal corre ctions is considered. A critical comparison between the experimental and th eoretical MDs allows us to determine the "optimum" wave function for cubane from the basis sets we studied. This wave function is then used to derive cubane's chemically interesting molecular properties. A summary of these re sults and a comparison of them with those of other workers is presented wit h the level of agreement typically being good.