High-order correlation contributions to the friction of macromolecules in solution: A semi-phenomenological Fokker-Planck approach

Institut für Physik, Universität Kassel - Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

Corresponding author: uvarov@physik.uni-kassel.de

Received: 19 February 2007
Accepted: 29 July 2007

Abstract

A novel, semi-phenomenological expression is derived for the friction tensor of macromolecules immersed into solution. By making a few realistic assumptions about the interaction of the molecular beads with the particles of the solvent, the friction tensor is expanded into a series of terms which purely depend on the -point correlation functions of the solvent as defined in the kinetic theory of the liquids. In a first application of this series expansion, the boundary condition coefficient is investigated for a single bead in dependence on the strength of the interaction among the solvent particles and with the macromolecule. When compared with previous molecular-dynamical simulations, excellent agreement is found even for a rather strong coupling between the bead and the solvent. Our new semi-phenomenological approach may therefore help extend the study of transport properties towards complex macromolecules in solution and will reduce the computational costs for that by several order of magnitude.