Relativistic Segmented Correlation Consistent Basis Sets for the 5p and 6p Elements.

The relativistic all-electron triple-ζ (TZ) and quadruple-ζ (QZ) correlation-consistent basis sets for the 5p and 6p elements were reoptimized to have a segmented contraction scheme. Properties computed with the segmented basis sets using the coupled-cluster level of theory with single, double, and perturbative triple excitations closely match the results obtained using the generally contracted analogues. Deviations in the ionization potentials and electron affinities computed using the segmented basis sets compared with those computed with the generally contracted basis sets are within 1 kcal mol. The relative deviation in the computed bond lengths for a selection of diatomic molecules is within 0.02 Å, and the computed harmonic vibrational frequencies differ by less than 3%. The mean absolute deviations (MADs) in the computed bond dissociation energies are 1.01 and 1.31 kcal mol for the TZ and QZ basis sets, respectively, when only the valence electrons are correlated and 0.14 and 0.10 kcal mol for the TZ and QZ basis sets, respectively, when the valence and outer-core electrons are correlated. The segmented basis sets also retain the systematically convergent behavior intrinsic to the correlation-consistent family of basis sets while affording speedups for the average time required to form the Fock matrix from 32.8 to 82.9× compared to the time required with the generally contracted versions when used with integral algorithms employed by many computational chemistry software packages.