Optimization of auxiliary basis sets for RI-MP2 and RI-CC2 calculations:: Core-valence and quintuple-ζ basis sets for H to Ar and QZVPP basis sets for Li to Kr

An implementation of analytic basis set gradients is reported for the optimization of auxiliary basis sets in resolution-of-the-identity second-order Moller-Plesset perturbation theory (RI-MP2) and approximate coupled-cluster singles-and-doubles (RI-CC2) calculations. The analytic basis set gradients are applied in the optimization of auxiliary basis sets for a number of large one-electron orbital basis sets which provide correlation energies close to the basis set limit: the core - valence basis sets cc-pwCVXZ (B - Ne, Al - Ar) with X = D, T, Q, 5, the quintuple-zeta basis sets cc-pV5Z (H - Ar) and cc-pV(5 + d) Z (Al - Ar) and the doubly-polarized valence quadruple-zeta basis sets QZVPP for Li-Kr. The quality of the optimized auxiliary basis sets is evaluated for several test sets with small and medium sized molecules.