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/|EMP2|) greater than 0.55 μEh per atom. In more than 90% of all cases the errors were smaller than 0.009 μEh. Moreover, these approximations affect molecular MP2 energies by less than 30 μEh per atom. In contrast to traditional attempts to optimize auxiliary basis sets, this approach is faster and more reliable.