Structures and Stabilities for Halides and Oxides of Transactinide Elements Rf, Db, and Sg Calculated by Relativistic Effective Core Potential Methods

Abstract

The ground states of the halides and oxides containing transactinide elements 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 two-component relativistic effective core potentials. Spin−orbit effects are rather small for geometries, harmonic vibrational frequencies, charge distributions, overlap populations, and dipole moments, but considerable for atomization energies. Electron correlations are necessary for any accurate determination of the molecular properties, in particular for the evaluation of atomization energies. The bond lengths of Sg compounds are consistently longer than those of the corresponding W compounds by 0.04−0.06 Å. The atomization energies for Sg compounds are slightly smaller than those for the corresponding W compounds due to spin−orbit and correlation effects. The differences tend to increase with the number of oxygen atoms in the compounds. Metal charges and dipole moments are larger for the Sg compounds than for the W compounds, implying that Sg is more ionic than W. The D3h structures are calculated to be more stable by about 2 kcal/mol than the C4v ones for TaCl5, TaBr5, DbCl5, and DbBr5.