While it would have been nice to fit to only the individual energy components of the model (E elec , E pol , E Pauli , etc.) and simply sum together their contributions to obtain an accurate interaction energy E int , small differences relative to each energy often resulted in much larger errors in E int . For example, Pauli repulsion energies increase exponentially as a function of atomic separation distance and their magnitude can be on the order of 10 2 to 10 3 kJ/mol (for example, see Figure ). Frozen electrostatics can also be almost twice that for hydrogen-bonded interaction energies. As a result, errors in E Pauli (or others), while small with respect to E Pauli itself, can contribute large errors with respect to E int . Errors in dispersion energies, on the other hand, are usually smaller if not equal to in magnitude as E int . Additionally, there is no guarantee that errors in other energy components should cancel and can instead enhance the overall error in E int . To this end, we choose to fit total interaction energies against dispersion energies with the same weight but instead use the logarithm of E Pauli to minimize the aforementioned transfer of errors between the remaining terms.