The subfigures show the data for the four different intra-domain weighting factor balancing strategies. For every setup, the density and RCE error curves intersect in the region where approximately 95% to 99% of the weight is assigned to the density. The location of the intersection is an interesting characteristic because it is an indicator for a well-balanced weighting factor distribution. Note that this does not necessarily correspond to the lowest combined error (i.e. the sum of the density and RCE errors). The intersections around "40-60" in figure (a) are caused by the optimization algorithm being stuck in a local minimum, which is a general problem for local optimization algorithms. The corresponding resulting parameter set also differs from the other resulting parameter sets (see tables 2, 3, 4 and 5 in section 5). Generally, the resulting parameter sets do not show a clearly favorable parameter combination (see figure ). Some combinations of the force field parameters σ H , C and partially σ C occur more frequently than others, but other combinations can result in similar or even lower loss function values.