(tail 1). The difference in tilt angles between the two MMG analogs is most pronounced in the single bilayer structure (Figures ). Average tail-to-headgroup tilt angles showed a trend of larger angles for MMG-1 in comparison to the case for MMG-6, suggesting a less tilted orientation of the headgroup relative to the hydrocarbon tails (Figure ). However, these angles were widely distributed in all cases. We analyzed two splay angles: the C9-C5-C22 splay angle close to the lipid acid moiety (splay 1) and the C20-C5-C35 splay angle, which considers the full length of the tails (splay 2) (Figure ). Both MMG-1 and MMG-6 molecules show similar distributions of splay angles, with three distinct peaks of splay 1. With splay 1, for all the cases, the majority of the lipids have the upper part of their tails forming an angle close to 95°and a second angle close to 120°(Figures ). A small population of angles also exists around 150°. With MMG-6, however, the probability distribution is more evenly spread between the first two peaks. This indicates a higher probability for a larger splay near the area connecting the glycerol and the lipid acid moiety. A larger splay angle means that these lipids are more likely to take up a larger volume within the membrane. Our APL xy and APL vor results support this idea. The probabilities of splay angle 2 show higher similarity between the systems, the majority of the splay angles being close to 15°(Figure ). This angle corresponds to a closed-tail conformation. A second, more subtle, peak can be seen at approximately 27°. Both splay 1 and splay 2 show a shift in the ratio of the peaks in the interdigitated system for MMG-1 with the second peak being more prominent than in other systems. This can be explained by the results from the clustering analysis presented in the next section (Figure ). A similar shift is seen between the single/double/interdigitated systems. The positions of the peaks are constant, just the ratio of the components differs. A similar trend was not observed in the case of MMG-6.