Path Integral Molecular Dynamics within the Grand Canonical-like Adaptive Resolution Technique: Simulation of Liquid Water

TL;DR

This paper integrates Path Integral Molecular Dynamics with the Grand-Canonical Adaptive Resolution Scheme to efficiently simulate liquid water, enabling larger and longer simulations while maintaining accuracy.

Contribution

It introduces a novel combination of PIMD with GC-AdResS for simulating liquid water, overcoming computational limitations of traditional PIMD methods.

Findings

Results agree well with full PIMD simulations and literature data.

The method effectively captures quantum effects in liquid water.

Simulation of larger systems is feasible with maintained accuracy.

Abstract

Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however computationally this technique is very demanding. The abovementioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One possible solution to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in literature. The comparison of our results with those reported in literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement.