Lateral Diffusion in a Binary Lipid System by a Computer Simulation Model

Document Type

Article

Publication Date

1-15-1996

Department

Physics and Astronomy

School

Mathematics and Natural Sciences

Abstract

A computer simulation model is used to study the lateral diffusion in a two-dimensional binary mixture of large and small particles. The small particle represents the phospholipid while the large particle (square) models the planar macromolecule in the binary mixture. The variation of the rms displacement with time of these molecular species are studied as a function of their concentration and their diffusion constants are examined. The concentration of the large particles (p1), small particles (p2), and the vacancy (p3) are varied at the relative area fraction Ae = p3/(p2 + p3) = 0.30 (low) and 0.60 (high) free area fractions. The diffusion constant of the small particles decays on decreasing their concentration - this decay signals the possibility of a transition between a fast diffusive regime (at high concentration) and a slow diffusive regime (at low concentration p2). The diffusion constant of the large molecules on the other hand shows an opposite behavior, it decays linearly on increasing their concentration (p1). The diffusion constant of the large molecule decays with their size while that of the small particles remains less affected by varying the size of the large molecules. The decay of the diffusion constant of the large molecule with its linear size is found to be nonlinear.

Publication Title

Physica A: Statistical Mechanics and its Applications

Volume

223

Issue

3-4

First Page

309

Last Page

320

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