Advantages and challenges in coupling an ideal gas to atomistic models in adaptive resolution simulations

TL;DR

This paper explores coupling water to an ideal gas in adaptive resolution simulations, highlighting the benefits and challenges, and demonstrating the feasibility with current methods.

Contribution

It investigates the coupling of water to an ideal gas in adaptive simulations, addressing energetic imbalances and demonstrating successful implementation.

Findings

Coupling water to an ideal gas is feasible with current adaptive methods.

Energetic imbalance poses challenges in smooth coupling.

The approach offers computational efficiency advantages.

Abstract

In adaptive resolution simulations, molecular fluids are modeled employing different levels of resolution in different subregions of the system. When traveling from one region to the other, particles change their resolution on the fly. One of the main advantages of such approaches is the computational efficiency gained in the coarse-grained region. In this respect the best coarse-grained system to employ in the low resolution region would be the ideal gas, making intermolecular force calculations in the coarse-grained subdomain redundant. In this case, however, a smooth coupling is challenging due to the high energetic imbalance between typical liquids and a system of non-interacting particles. In the present work, we investigate this approach, using as a test case the most biologically relevant fluid, water. We demonstrate that a successful coupling of water to the ideal gas can be achieved with current adaptive resolution methods, and discuss the issues that remain to be addressed.