Parameters of the ELBA force field.

Subscripts , , , , , and stand for the site types choline, amine, phosphate, glycerol, ester, tail and water, respectively. Lennard-Jones cross-terms are calculated by the standard Lorentz-Berthelot rules [23] except for increased terms representing hydrogen bonding; in particular, , , , , are set as reported in the table. Charges and dipoles are identified by and ; cross terms are obtained via standard electrostatic formulae [35]. The rigidity of the Hooke harmonic potential (equation 4) is identified by ; reference lengths are set to . The rigidity of the angle potential (equation 5) is identified by ; reference angles are reported for the relevant triplets of sites. The rigidity of the orientation-restraining potential (equation 10) is . Masses and principal moments of inertia are identified by and , respectively.