A b i n i t i o studies of the electronic structrue of UF6, UF6+, and UF−6 using relativistic effective core potentials

Abstract
Ab initio calculations are performed on the electronic states of UF6, UF6+, and UF6 using a relativistic effective core potential (ECP) for uranium and a nonrelativistic ECP for fluorine. In most of the calculations 56 valence electrons are treated explicitly using a contracted [3s3p2d2f/2s2p] Gaussian basis. Various ECP’s were explored, but all yield an overall charge density of U+2.4 (F−0.4)6. The bonding in the ground state of UF6 is discussed. SCF and CI calculations on UF6+ are compared with the experimental photoelectron spectrum and with previous scattered‐wave calculations. The role of spin–orbit coupling in the states of UF6+ and UF6 is discussed. The calculated electron affinity of UF6 (7.1 eV) is considerably larger than the current experimental estimates, but the relative energies of the states of UF6 are in excellent agreement (0.1–0.2 eV) with experiment.