Altogether these results indicate that an optimal solution was found for parametrizing the bonded terms of Martini lipid models using the alternative Representation 1, according to the objectives defined. Structural properties appear improved for the selected lipids in the liquid phase and in the gel phase specifically for DPPC, the bonded parameters having been calibrated in order to obtain an optimal compromise specifically to this end. However, because Representation 1 makes use of repeated small and big beads for modeling saturated tails (Fig. ), the lateral packing of the tails cannot be correctly described in the gel phase notably for DMPC and DSPC. In particular, when tested a posteriori the transition in between liquid and gel phases is not observed for DMPC and the transition temperature is not respected for DSPC (Fig. ). Repeating this parametrization experiment and including in the training set also simulations of DMPC and DSPC bilayers in the gel phase (273K and 308K, respectively) does not allow to further improve the models. Instead, this additional experiment shows that no satisfying solution can be found for parametrizing towards these objectives the bonded parameters of lipid models using the philosophy of Representation 1 (Fig. ).