Brownian dynamics simulations of flexible polymers with spring–spring repulsions

We develop a method which incorporates spring–spring repulsions into Brownian dynamics simulations of flexible polymers. The distance of closest approach between two springs is computed, and a repulsive force is then applied based on this distance. Repulsive potentials of the exponential and power-law forms are considered. We demonstrate that our method is capable of accounting for excluded-volume effects in start-up of extensional flow. Equilibrium simulations indicate that spring-spring repulsions can be used to prevent the passage of two springs through each other, and thus maintain the topological integrity of polymer molecules. The method developed here is expected to be useful for simulating entanglement phenomena in both single and multichain systems.