Dynamics of Charged Polymers. 1

We use full classical dynamics to study the properties of isolated multiply charged polymeric ions. The polymer is taken to be a chain of 1000 “atoms” with bonding and nonbonding potential terms; in these initial studies, no polarization or dielectric terms are included. We treat polymers with 1, 5, 10,15, and 20 charges equally spaced along the 1000 atom chain and conduct a 600-ps simulation of the charged species. Each simulation required approximately 7 h on a Cray YMP. Because the simulation is limited in time and the potential adopted is relatively simple, the results are interpreted qualitatively as a function of charge density. At high charge densities the ions force the polymeric ion to adopt a stretched out, essentially planar conformation, in marked contrast to the highly folded conformation adopted by an uncharged polymer. This conformation minimizes the ionic interactions within the constraints imposed by chemical bonding. These descriptions are supported by the statistical data obtained during the simulation.