Comparison of ab initio and density functional methods for TeF6

The molecular geometry and vibrational frequencies of TeF6 have been calculated using different quantum chemical (Hartree–Fock, MP2, DFT) theories in conjunction with various basis set combinations including relativistic effective core potentials supplemented with polarised double- and triple-zeta valence basis sets for Te and with a 6-31+G*, 6-311+G* and Dunningʹs correlation consistent bases for F. The results demonstrate that the errors of the individual theories and basis sets are fairly systematic. Investigating the basis set convergence for the molecular geometry, an increase of the valence basis of tellurium resulted in negligible alteration of the calculated bond length. On the other hand, the results were sensitive to the basis set of fluorine. An augmented correlation consistent triple-zeta basis was required to provide theoretical results in agreement with experiment.