An all-atomistic force field (FF) for saturated PC lipids coined Stockholm lipids (Slipids). All parameters have been developed in a consistent and physical sound way. All the partial atomic charges have been recalculated at the B3LYP/cc-pVTZ level of theory by fitting the electrostatic potential. Lennard-Jones and torsional parameters were refitted from experimental data and high level ab-initio calculations, respectively. The remaining parameters are taken from C36.

The abilities of Slipids is proven in J. Phys. Chem. B, 2012, 116 (10), 3164-3179 (http://pubs.acs.org/doi/abs/10.1021/jp212503e, open access) and J. Chem. Theory Comput., 2012, DOI: 10.1021/ct300342n. A number of experimental properties such as area per lipid and thicknesses are reproduced. More importantly, X-ray and neutron scattering form factors and NMR order parameters are in excellent agreement with experiments for a range of temperatures.

Slipids is compatible with FFs from the AMBER family for amino acids. Tests with AMBER99SB, AMBER99SB-ILDN and AMBER03 together with Slipids have been performed with microsecond simulations and show that they can be mixed. Free energies of transfer of amino acid analogues from water to cyclohexane has also been calculated and are in good agreement with experimental data.

See http://people.su.se/~jjm for more parameters and related data such as structures etc.