DENSITY-FUNCTIONAL COMPUTATIONS FOR INNER-SHELL EXCITATION SPECTROSCOPY

The 1s --> pi inner-shell excitation spectra of seven molecules have been studied using density functional theory along with the unrestrict ed generalized transition state (uGTS) approach. The exchange-correlat ion potential is based on a combined functional of Becke's exchange (B 88) and Perdew's correlation (P86). A scaling procedure based on Cleme nti and Raimondi's rules for atomic screening is applied to the cc-pVT Z basis set of atoms where a partial core-hole is created in the uGTS calculations. The average absolute deviation between our predicted 1s --> pi excitation energies and experimental values is only 0.16 eV. S inglet-tripler splittings of C 1s --> pi transitions of CO, C2H2, C2H 4, and C6H6 also agree with experimental observations. The average abs olute deviation of our predicted core-electron binding energies and te rm values is 0.23 and 0.29 eV, respectively.