The standard and cryst saaPCVA calculation were performed analogously to those of COMT and the subsequent evaluation again delivered sensitivities and QM region indicators for each amino acids (see Figs. and). Based on the indicator ranking of the standard approach, new QM regions were constructed which are equal in size to the distance-based ones. The composition of these regions can be found in Table . Subsequently, the convergence of the VDD charges and reaction energies was investigated and gPCVA was applied to these systematically constructed QM regions (Fig. ).