Variational theory for a single polyelectrolyte chain revisited |
| |
Authors: | Manghi M Netz R R |
| |
Institution: | (1) Sektion Physik, Ludwig Maximilian University, Theresienstr. 37, 80333 Munich, Germany |
| |
Abstract: | We reconsider the electrostatic contribution to the persistence length,
, of a single, infinitely long-charged polymer in the presence of screening. A Gaussian variational method is employed, taking
as the only variational parameter. For weakly charged and flexible chains, crumpling occurs at small length scales because conformational fluctuations overcome electrostatic repulsion. The electrostatic persistence length depends on the square of the screening length,
, as first argued by Khokhlov and Khachaturian by applying the Odijk-Skolnick-Fixman (OSF) theory to a string of crumpled blobs. We compare our approach to previous theoretical works (including variational formulations) and show that the result
found by several authors comes from the improper use of a cutoff at small length scales. For highly charged and stiff chains, crumpling does not occur; here we recover the OSF result and validate the perturbative calculation for slightly bent rods.PACS:
36.20.-r Macromolecules and polymer molecules - 82.70.-y Disperse systems; complex fluids - 87.15.-v Biomolecules: structure and physical properties |
| |
Keywords: | |
本文献已被 PubMed SpringerLink 等数据库收录! |
|