@article {2008|1866,
	title = {United-Atom Acyl Chains for {CHARMM} Phospholipids},
	journal = {J. Phys. Chem. B.},
	volume = {112},
	number = {23},
	year = {2008},
	pages = {7008{\textendash}7015},
	publisher = {Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104-6323, and Research Institute for Computational Sciences, National Institute of Advanced Industrial Science and Technol},
	abstract = {In all-atom simulations of lipid membranes, explicit hydrogen atoms contained in the hydrocarbon region are described by a large number of degrees of freedom, although they convey only limited physical information. We propose an implicit-hydrogen model for saturated and monounsaturated acyl chains, aimed at complementing the all-atom CHARMM27 model for phospholipid headgroups. Torsional potentials and nonbonded parameters were fitted to reproduce experimental data and free energy surfaces of all-atom model systems. Comparative simulations of fluid-phase POPC bilayers were performed using the all-hydrogen force field and the present model. The hybrid model accelerates a typical bilayer simulation by about 50\% while sacrificing a minimal amount of detail with respect to the fully atomistic description. In addition, the united-atom description is energetically compatible with all-atom CHARMM models, making it suitable for simulations of complex membrane systems.},
	doi = {10.1021/jp800687p},
	author = {J{\'e}r{\^o}me H{\'e}nin and Wataru Shinoda and Michael L Klein}
}
