Non-Aqueous Ion Pairing Exemplifies the Case for Including Electronic Polarization in Molecular Dynamics Simulations

TL;DR

This study demonstrates that including electronic polarization via charge scaling in molecular dynamics simulations significantly improves the accuracy of modeling ion interactions, especially in non-aqueous environments, and supports its use in biomolecular simulations.

Contribution

The paper provides ab initio evidence validating the electronic continuum correction approach for modeling ion pairing, highlighting its importance in force field development.

Findings

Electronic polarization reduces overestimated ion interactions.

Charge scaling factors can be optimized for better force field accuracy.

Results support applying polarization effects in biomolecular simulations.

Abstract

The inclusion of electronic polarization is of crucial importance in molecular simulations of systems containing charged moieties. When neglected, as often done in force field simulations, charge-charge interactions in solution may become severely overestimated leading to unrealistically strong bindings of ions to biomolecules. The electronic continuum correction introduces electronic polarization in a mean-field way via scaling of charges by the reciprocal of the square root of the high-frequency dielectric constant of the solvent environment. Here, we use ab initio molecular dynamics simulations to quantify the effect of electronic polarization on pairs of like-charged ions in a model non-aqueous environment where electronic polarization is the only dielectric response. Our findings confirm the conceptual validity of the present approach, underlining its applicability to complex aqueous biomolecular systems. Simultaneously, the present results justify the potential employment of weaker charge scaling factors in force field development.