In most of the currently used force fields, these two strategies have been used in conjunction with one another, usually by obtaining the starting point from QM calculations and then re-adjusting some parameters targeting experimental data. While force fields calibrated with this approach during the last decades have reached impressive performance, they also have severe flaws, as outlined in the sections above. The ever growing need for more accurate force fields and more realistic description of the underlying physics such as electronic polarization is a strong incentive to speed up the parameterization process using automated approaches.