We next evaluated whether previously suggested structural changes that take place within L o phase are present in our simulations. As shown in Fig. , the mean tilt angle of DPPC chains shows two different slopes with crossovers at T co , in line with the predicted variation in chain tilting within the L o region. Clarke et al. and Reinl et al. suggested that temperature increase within the L o phase shifts CHOL towards the headgroup region, leading to the disordering of the lipid chain terminal carbons. This repositioning of CHOL towards the headgroup region indeed takes place (Fig. ), which further decreases acyl chain ordering in the membrane core. Indeed, as shown in Fig. , the mean deuterium order parameter of the last 9 carbons of the DPPC sn-2 chain displays crossovers at T co . The glycerol region melting, suggested to occur within the L o phase by Clarke et al., The mean order parameter of all DPPC sn-2 chains, starting from the 8 th carbon, i.e. the middle of the chain. The carbonwise order parameter plots are shown in Fig. . C) Mean order parameter of DPPC chains as a function of cluster identity (bars) and the fractions of the different cluster identities (lines). "Core" chains are surrounded by hexagonally-packed chains, "free" chains are not part of a hexagonally-packed cluster, and "edge" points roughly correspond to the cluster edges.