title: Molecular dynamics simulation of hydrated DPPC monolayers using charge equilibration force fields.
abstract: We present results of molecular dynamics simulations of a model DPPC-water monolayer using charge equilibration (CHEQ) force fields, which explicitly account for electronic polarization in a classical treatment of intermolecular interactions. The surface pressure, determined as the difference between the monolayer and pure water surface tensions at 323 K, is predicted to be 22.92 ±1.29 dyne/cm, just slightly below the broad range of experimental values reported for this system. The surface tension for the DPPC-water monolayer is predicted to be 42.35 ±1.16 dyne/cm, in close agreement with the experimentally determined value of 40.9 dyne/cm. This surface tension is also consistent with the value obtained from DPPC monolayer simulations using state-of-the-art nonpolarizable force fields. The current results of simulations predict a monolayer-water potential difference relative to the pure water-air interface of 0.64 ±0.02 Volts, an improved prediction compared to the fixed-charge CHARMM27 force field, yet still overestimating the experimental range of 0.3 to 0.45 Volts. As the charge equilibration model is a purely charge-based model for polarization, the current results suggest that explicitly modeled polarization effects can offer improvements in describing interfacial electrostatics in such systems.
authors: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
authors: Timothy R
authors: TR
authors: Lucas
authors: Brad A
authors: BA
authors: Bauer
authors: Joseph E
authors: JE
authors: Davis
authors: Sandeep
authors: S
authors: Patel
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D008567:Membranes, Artificial; D056004:Molecular Dynamics Simulation; D014867:Water / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine