Conformational Behavior of Single Circular Semiflexible Polyelectrolyte in the Presence of Multivalent Counterions

Langevin dynamics simulations are employed to explore the effects of chain stiffness and electrostatic interaction (EI) on the conformational behavior of a circular semiflexible polyelectrolyte (CSPE) in presence of trivalent counterions. We investigate the effect of bending energy b and the dimensionless Bjerrum length A on the conformational behaviour of the CSPE with a fixed chain length. The competition among the EIs, chain stiffness and entropy of the system leads to rich conformations for the CSPE. As the b is less than or equal to 50, The shape of the CSPE changes from a oblate ring to a rod at small A , then to a toroid at intermediate A , and finally to a globule at very large A . However, the globular conformation is not observed for large b . In addition, we find that the number of torus ring increases with A increase, while decreases with b increase. This study should be helpful in gaining insight into the conformational behaviour of charged biopolymer.