• Variational optimization of all basis set parameters in Eqs. 7, 8, and 9 in both atomic and molecular calculations. See the Technical Details section below for an in-depth explanation of the optimization process, and Refs. 13,41 for a more extensive perspective on the background of molecule-optimized basis sets. a The ECP was taken from the TURBOMOLE basis set library, with the h projector being removed from the published ECP.