Energy-consistent pseudopotentials for the 5d elements--benchmark calculations for oxides, nitrides, and Pt(2).

The performance of new relativistic energy-consistent pseudopotentials for the 5d elements, adjusted to atomic valence spectra from multiconfiguration Dirac-Hartree-Fock calculations (J. Chem. Phys. 2009, 130, 164108.), is examined in coupled cluster and multireference configuration interaction benchmark calculations for the diatomics HfO, TaO, WO, ReN, OsN, IrN, and Pt(2), with basis sets of up to quintuple-zeta quality. The final accuracy reached for the oxides and nitrides, with corrections for pseudopotential errors (contributions from 4f shell correlation, for example), is 0.3 pm for bond lengths and 17 cm(-1) (1.5%) for harmonic vibrational frequencies. The spectroscopic constants of the ground state of Pt(2) can be reproduced with deviations of 3 pm for the bond length and 1 cm(-1) for the vibrational frequency, without any correction for pseudopotential errors.