Segmented contraction scheme for small-core actinide pseudopotential basis sets

Gaussian (14s13p10d8f6g)/[10s9p5d4f3g] valence basis sets using a segmented contraction scheme have been derived for relativistic energy-consistent small-core actinide pseudopotentials of the Stuttgart-Koln variety. The present basis sets are only slightly larger than previously published (14s13p10d8f6g)/[6s6p5d4f3g] atomic natural orbital basis sets, which use a generalized contraction scheme, and achieve a similar accuracy in atomic and molecular calculations. For calibration purposes multi-configuration self-consistent field and subsequent multi-reference averaged coupled-pair functional calculations are presented for the first to fourth ionization potentials of all actinide elements. In addition, results of molecular calibration studies using the coupled-cluster singles, doubles and perturbative triples approach as well as gradient-corrected density functional theory are reported for the monohydrides, monoxides and monofluorides of actinium and lawrencium. (C) 2003 Elsevier B.V. All rights reserved.