Segmented correlation consistent basis sets for the 4d and 5d transition metals

The cc-pVnZ-PP and cc-pwCVnZ-PP (n = D, T, Q, 5) pseudopotential-based correlation consistent basis sets for the 4d and 5d transition metals were reoptimized to have segmented contraction schemes. Computed ionization potentials and dⁿs² → dⁿ⁺¹s¹ excitation energies computed at the coupled cluster level of theory with single, double, and perturbative triple excitations using the segmented basis sets approximate the result obtained with the generally contracted basis sets with mean absolute deviations (MADs) within 0.75 kcal mol^-1 for the ionization energies and 2 kcal mol^-1 for the excitation energies with respect to the results obtained with the generally contracted basis. The segmented basis sets also retain the systematically convergent behavior of the correlation consistent basis sets with MADs within 0.61 kcal mol^-1 with respect to the generally contracted basis for properties extrapolated to the complete basis set limit. The segmented nature of the seg-cc-pVnZ-PP and seg-cc-pwCVnZ-PP basis sets enables significant performance improvements when using algorithms with an a priori treatment of the contraction coefficients with average speedups in the time required to form the Fock matrix ranging from 6.1× for the seg-cc-pVDZ-PP basis sets to 53.8× for the seg-cc-pV5Z-PP basis sets.