A meso-scale simulation method for polymers

Polymers are important and are widely used in many industrial and scientific applications. Their versatility stems from complex constituents and structures that exhibit multiple length and time scales, thus computer simulations serve as a powerful tool to understand polymers. Molecular Dynamics is among the most popular computational methods in this field. However, explicitly resolving solvent molecules is computationally expensive, making it challenging to scale the problem size to real applications, while implicit-solvent representations do not yet model full hydrodynamics. On the other hand, Brownian Dynamics can faithfully capture hydrodynamic interactions using Green’s functions, but with a tradeoff of having to invert a dense mobility matrix. We have recently developed a meso-scale fluid model, the Discrete-Ion Stochastic Continuum Overdamped Solvent (DISCOS) algorithm, and in this work, we extend it to simulate polymeric systems. In DISCOS, the solvent is modeled using fluctuating hydrodynamics, and polymers are simulated via spring-bead model by the immersed boundary method. We validate DISCOS by first simulating a single-chain polymer and comparing to Rouse and Zimm model, and then generalize to multi-chain systems such as membranes.