Gaussian basis sets for molecular calculations. The representation of 3d orbitals in transition-metal atoms

Abstract

Augmented (4d) and (5d) Gaussian basis sets are presented which provide a balanced description of the 4s²3dⁿ⁻², 4s3dⁿ⁻¹, and 3dⁿ configurations of transition−metal atoms. When compared to accurate Hartree–Fock calculations, the (4d) and (5d) expansions in the literature, which have been optimized for the 4s²3dⁿ⁻² configuration, can lead to errors of several eV for states of the latter configurations where the 3d orbitals become more diffuse. The augmented sets reported here consist of a single diffuse basis function added to the original sets, where the orbital exponent of the added function was optimized for the 3dⁿ configuration. Basis sets and contraction schemes are presented for the atoms Sc through Cu.