7 research outputs found
Molecular Dynamics Simulations of Lipid Bilayers: Major Artifacts due to Truncating Electrostatic Interactions
We study the influence of truncating the electrostatic interactions in a
fully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer through 20 ns
molecular dynamics simulations. The computations in which the electrostatic
interactions were truncated are compared to similar simulations using the
Particle-Mesh Ewald (PME) technique. All examined truncation distances (1.8 to
2.5 nm) lead to major effects on the bilayer properties, such as enhanced order
of acyl chains together with decreased areas per lipid. The results obtained
using PME, on the other hand, are consistent with experiments. These artifacts
are interpreted in terms of radial distribution functions of molecules
and molecular groups in the bilayer plane. Pronounced maxima or minima in g(r)
appear exactly at the cutoff distance indicating that the truncation gives rise
to artificial ordering between the polar phosphatidyl and choline groups of the
DPPC molecules. In systems described using PME, such artificial ordering is not
present