Distribution of counterions near discretely charged planes and rodsM. L. Henle1, C. D. Santangelo1, D. M. Patel1 and P. A. Pincus1, 2, 3
1 Department of Physics, University of California - Santa Barbara, CA 93106, USA
2 Department of Materials, University of California - Santa Barbara, CA 93106, USA
3 Program in Biomolecular Science and Engineering, University of California Santa Barbara, CA 93106, USA
(Received 24 October 2003; accepted in final form 10 February 2004)
Realistic charged macromolecules are characterized by discrete (rather than homogeneous) charge distributions. We investigate the effects of surface charge discretization on the counterion distribution at the level of mean-field theory using a two-state model. Both planar and cylindrical geometries are considered; for the latter case, we compare our results to numerical solutions of the full Poisson-Boltzmann equation. We find that the discretization of the surface charge can cause enhanced localization of the counterions near the surface; for charged cylinders, counterion condensation can exceed Oosawa-Manning condensation.
82.70.-y - Disperse systems; complex fluids.
61.20.Qg - Structure of associated liquids: electrolytes, molten salts, etc.
82.35.Rs - Polyelectrolytes.
© EDP Sciences 2004