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arXiv · 2601.17244

Practical Considerations for Finite Concentrations Molecular Dynamics Simulations

Xiaoxu Ruan·Fabrice Roncoroni·David Prendergast·Tod A Pascal
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Abstract

Understanding concentrated electrolytes requires a theory that spans local hydration and mesoscale interfacial assembly. We present an integrated workflow-SCOPE-that combines (i) enhanced sampling focused on a single Li+ ion, (ii) reweighting of biased trajectories to recover equilibrium microstate probabilities, and (iii) a chemical-potential correction that accounts for the limited reservoir of free water in finite simulation boxes. Applied to LiCl(aq) across 0.5-26 M and 283-313 K, this approach reveals a simple organizing principle: solvated ions dominate at low concentration; contact ion pairs emerge at intermediate strength; and aggregated Li-xCl clusters become most stable at the solubility limit. The resulting free-energy trends predict temperature-dependent solubility in close agreement with experiment and clarify the role of interfacial nucleation in precipitation. Beyond the simple LiCl(aq) salt considered here, SCOPE offers a transferable strategy for characterizing speciation and phase behavior in concentrated liquid systems where collective coordinates and rare events dominate.

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Xiaoxu Ruan, Fabrice Roncoroni, David Prendergast, Tod A Pascal. 2026-01-24. Practical Considerations for Finite Concentrations Molecular Dynamics Simulations. https://doi.org/10.1063/5.0322052

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