Molecular Solvation with a Field Variant of Semi-Explicit Assembly

Here we present a field variant of the Semi-Explicit Assembly (SEA) model for molecular solvation. The original form of SEA can saturate its solvation response, leaving it with under-predicted hydration free energies for charge-dense solutes, like monatomic or molecular ions. This new version of SEA implements an adaptive solvation surface boundary and a polar charging free energy surface that can be uniquely accessed as a function of electric field and solvation surface curvature. We show that this new approach is quantitatively predictive with full explicit solvent hydration free energies non-polar, polar, and charged molecular solutes. We also show it can quantitatively predict hydration of amino acid dipeptides, providing a route to accurate assessment of hydration for larger biomolecule solutes.