(167h) Using Drude Oscillators to Capture Ion Solvation in Generic Coarse-Grained Molecular Dynamics Simulations of Polymer Electrolytes

Simple bead-spring models with Lennard-Jones (LJ) interactions between non-bonded beads are widely employed in the study of uncharged polymeric materials. When ions are present, additional model features are needed to account for their longer ranged interactions with each other (typically via Coulomb interactions) and for their interactions with polarizable polymers. Such features must be chosen with care to capture key phenomena of interest while maintaining good computational efficiency. Some prior work has captured ion-polymer solvation effects by including a point dipole in each polymer bead, which also effectively scales the Coulomb interactions. We aim to consider our coarse-grained model beads, which represent groups of atoms with multiple internal dipoles that can rearrange with respect to each other, as polarizable entities, but in a simplified manner. In particular, much of our prior work has applied ion-polymer interactions that scale as r^-4 (as for ion to induced dipole interactions), while also uniformly scaling Coulomb interactions down to account for the dielectric constant. The conceptually similar but more explicit and expensive method of adding Drude oscillators to each bead has also been used by others, and does not require the assumption of a uniform dielectric medium for ion-ion interactions. Here, we perform a range of test simulations to understand the types of systems in which applying the more exact Drude oscillator model may be needed to capture details of ion dynamic behavior, especially near interfaces. We will also compare the computational efficiency between models with explicit Drude oscillators and implicit solvation potential.