In order to study the influence of higher order contributions such as cubic charge transfer models and the influence of perturbations for the electronegativities and chemical hardnesses, we fitted the data for the experimental and the computed HSPs with the corresponding models as listed in Eqns. ( ) -( ) in the supporting information. The results are compared to the simple HSP fitting approach (Eqn. ( )) in order to evaluate the influence of further and higher order contributions. More details on the individual fitting equations can be found in the supporting information. In the following, we list the corresponding values as well as error estimates of the models for all solvents and for solvents with D < 5 Debye separately.