Accurate density-functional calculation of core-electron binding energies with a scaled polarized triple-zeta basis set .3. Extension to open-shell molecules

Density functional theory and the unrestricted generalized transition state (uGTS) model were applied to study the core-electron binding energies (CEBEs) of open-shell molecules. Basis set scaling based on Clementi and Raimondi’s rules for atomic screening was used along with the cc-pVTZ basis set. The scaled pVTZ basis set is almost as good as the cc-pV5Z and complete basis set limit in predicting CEBEs. For small molecules (O-2, NO, NF2 and NO2) the average absolute deviation (aad) of our prediction (scaled pVTZ) is only 0.29 eV. For the larger molecule (CF3)(2)NO the aad is 0.56 eV, compared with experimental uncertainty of 0.5 eV. Theoretical predicted multiplet splittings for the small molecules agree quite well with experiment: the average deviation is -0.33 eV. For (CF3)(2)NO the calculated multiplet splittings are much smaller than the experimental ones. We also predict the CEBEs of PO, SN and SO, which have not been observed experimentally. (C) 1997 Elsevier Science B.V.