Structures and stabilities for halides and oxides of transactinide elements Rf, Db, and Sg calculated by relativistic effective core potential methods

The ground states of the halides and oxides containing transactinide elemen ts Rf (element 104), Db (element 105), and Sg (element 106) were calculated at the HF, MP2, QCISD, CCSD, and CCSD(T) levels of theory using one- and t wo-component relativistic effective core potentials. Spin-orbit effects are rather small for geometries, harmonic vibrational frequencies, charge dist ributions, overlap populations, and dipole moments, but considerable for at omization energies. Electron correlations are necessary for any accurate de termination of the molecular properties, in particular for the evaluation o f atomization energies. The bond lengths of Sg compounds are consistently l onger than those of the corresponding W compounds by 0.04-0.06 Angstrom. Th e atomization energies for Sg compounds are slightly smaller than those for the corresponding W compounds due to spin-orbit and correlation effects. T he differences tend to increase with the number of oxygen atoms in the comp ounds. Metal charges and dipole moments are larger for the Sg compounds tha n for the W compounds, implying that Sg is more ionic than W. The D-3h stru ctures are calculated to be more stable by about 2 kcal/mol than the C-4 up silon ones for TaCl5, TaBr5, DbCl(5), and DbBr(5).