Using Drude Oscillators to Capture Ion Solvation in Generic Coarse- Grained Molecular Dynamics Simulations of Polymer Electrolytes

MD Fan and LM Hall, MACROMOLECULES, 58, 754-766 (2024).

DOI: 10.1021/acs.macromol.4c02082

Generic bead-spring models with Lennard-Jones interactions are commonly used to study uncharged polymeric materials. However, incorporating ions into polymer systems requires additional model features to address their long-ranged Coulomb interactions and their interactions with polarizable polymers. This study integrates the Drude oscillator model into coarse- grained molecular dynamics simulations to capture features of ion solvation in polymers. Specifically, we treat coarse-grained beads as polarizable entities with internal dipoles; each bead contains a Drude core bonded with a stiff spring to an oppositely charged Drude particle that does not leave the Lennard-Jones diameter of the core. We first demonstrate the feasibility of this approach in simulations of neat polymers, exploring dielectric constants ranging from 2 to 12. To manage strong local interactions in high-polarizability systems with ions, we propose combining this approach with implicit strategies such as adjusting the background dielectric constant and scaling down ion charges. By combining these explicit and implicit methods, we can gain control over structural features like ion clustering and peak heights in radial distribution functions, enhancing our ability to model features of ion solvation and dielectric response in polymer systems.

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