Session H39: Lipid Bilayers: Structure and Function I
8:00 AM–11:00 AM, Tuesday, March 17, 2009
Room: 411
Sponsoring Unit:
DBP
Chair: Alex Levine, University of California, Los Angeles
Abstract ID: BAPS.2009.MAR.H39.12
Abstract: H39.00012 : Subdiffusion and diffusion of lipid atoms and molecules in phospholipid bilayers
10:12 AM–10:24 AM
Preview Abstract
MathJax On | Off 
Abstract 
Authors:
Elijah Flenner
(Colorado State University)
Jhuma Das
(University of Missouri-Columbia)
Maikel Rheinstadter
(University of Missouri-Columbia)
Ioan Kosztin
(University of Missouri-Columbia)
We examine the dynamics of lipid atoms and molecules using a 0.1 $\mu$s all-atom molecular dynamics simulation of a hydrated diyristoyl-phosphatidycholine (DMPC) lipid bilayer. We identify three well separated time regimes in the mean square displacement, $\langle \delta r^2(t) \rangle$, of the lipid atoms and molecules: (1) a ballistic regime for $t<10$ femptoseconds; (2) a subdiffusive regime where $\langle \delta r^2(t) \rangle \sim t^\beta$ and $\beta < 1$ for times between 10 picoseconds and 10 nanoseconds; and (3) a Fickian diffusion regime where $\langle \delta r^2(t) \rangle \sim t$ for $t > 30$ nanoseconds. We propose a memory function approach for describing the mean square displacement over the whole time range, and find that the lateral self diffusion coefficient found from the memory function approach agrees well with the one determined from the mean square displacement. We use the cumulant expansion of the self-intermediate scattering function to connect the three time scales in the mean square displacement to the interpretation of neutron scattering signals.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.H39.12