The Q-AMOEBA (CF) Polarizable Potential

TL;DR

This paper introduces Q-AMOEBA (CF), a polarizable water model incorporating geometry-dependent charge flux and nuclear quantum effects, achieving high accuracy in thermodynamic and biochemical property predictions.

Contribution

The paper develops and validates Q-AMOEBA (CF), a novel polarizable force field that explicitly includes charge flux and nuclear quantum effects, improving accuracy over existing models.

Findings

Accurately reproduces experimental water structure data.

Provides reliable thermodynamic property predictions for water.

Reveals significant nuclear quantum effects in hydration free energies.

Abstract

We present Q-AMOEBA (CF), an enhanced version of the Q-AMOEBA polarizable model that integrates a geometry-dependent charge flux (CF) term while designed for an explicit treatment of nuclear quantum effects (NQE). The inclusion of CF effects allows matching experimental data for the molecular structure of water in both gas and liquid phases, addressing limitations faced by most force fields. We show that Q-AMOEBA (CF) provides highly accurate results for a wide range of thermodynamical properties of liquid water. Using the computational efficiency of the adaptive Quantum Thermal Bath method, which accounts for NQE at a cost comparable to classical molecular dynamics, we evaluate the robustness and transferability of Q-AMOEBA (CF) by calculating hydration free energies of various ions and organic molecules. Finally, we apply this methodology to the alanine dipeptide and compute the corresponding dihedral angle potential of mean force and hydration free energy. Unexpectedly, the latter quantity displays significant NQE. These results pave the way to a finer understanding of their role in biochemical systems.