Global and local optimization of auxiliary basis sets for RI-MP2 calculations

Abstract

Optimization approaches using several global and local algorithms (genetic algorithms, direct search and implicit filtering) in the search for a global minimum are applied to optimize auxiliary basis sets for quantum chemistry ab initio calculations. We optimize mixed Poisson and density auxiliary basis sets for RI-MP2, by minimizing a suitable objective function ΔI. For H, B, C, N, O and F optimized auxiliary basis sets are reported for cc-pVXZ (X = D, T and Q). The auxiliary basis sets optimized in this work are all even-tempered series. As results from these approaches, we never observed errors (ΔI/|E_MP2|) greater than 0.55 μE_h per atom. In more than 90% of all cases the errors were smaller than 0.009 μE_h. Moreover, these approximations affect molecular MP2 energies by less than 30 μE_h per atom. In contrast to traditional attempts to optimize auxiliary basis sets, this approach is faster and more reliable.