Molecular dynamics in a grand ensemble: Bergmann–Lebowitz model and adaptive resolution simulation

Abstract

This article deals with the molecular dynamics simulation of open systems that can exchange energy and matter with a reservoir; the physics of the reservoir and its interactions with the system are described by the model introduced by Bergmann and Lebowitz (P G Bergmann and J L Lebowitz 1955 Phys. Rev. 99 578). Despite its conceptual appeal, the model did not gain popularity in the field of molecular simulation and, as a consequence, did not play a role in the development of open system molecular simulation techniques, even though it can provide the conceptual legitimation of simulation techniques that mimic open systems. We shall demonstrate that the model can serve as a tool in devising both numerical procedures and conceptual definitions of physical quantities that cannot be defined in a straightforward way by systems with a fixed number of molecules. In particular, we discuss the utility of the Bergmann-Lebowitz (BL) model for the calculation of equilibrium time correlation functions within the grand canonical adaptive resolution method (GC-AdResS) and report numerical results for the case of liquid water.

Ionic Liquids Treated within the Grand Canonical Adaptive Resolution Molecular Dynamics Technique

“…In this study we employ the Grand Canonical Adaptive Resolution Simulation Scheme (GC-AdResS) for molecular dynamics [25,26,[28][29][30]38]. Two regions of a simulation box having different resolution regions: 1. atomistic (AT) and 2. a coarse-grained (CG) system can be linked using this multi-resolution simulation method.…”

“…Studies have shown that models that can reproduce macroscopic thermodynamic quantities such as density and temperature can be used as coarse-grained models, so that AdResS is re-framed within the Grand Ensemble idea of open boundary systems [29,30,38]. In this work, we use a spherical atomistic region of radius d at that is surrounded by a hybrid region of width d hy .…”

“…However, in our previous studies on ILs, we have shown that a large class of ILs can be characterized by a local scale where important properties that may be expected to be dominated by large scale pair correlations, are instead highly localized and depend only on the immediate neighboring molecules [22][23][24]. Motivated by these results, the adaptive resolution scheme (AdResS) [25,26] has been extended to grand canonical-like version [27][28][29][30] for the study of ILs.…”

Probing spatial locality in ionic liquids with the grand canonical adaptive resolution molecular dynamics technique

“…AdResS is re-framed within the Grand Canonical approach 28,29 , or even further, within the more general Grand Ensemble idea of open boundary systems 30,31,38 . For the specific study in this work, the atomistic region is modelled as a sphere of radius d at and is surrounded by a spherical hybrid region of width d hy and the remainder of the box is the CG region that serves as a particle reservoir for the AT region; see the pictorial representation in Fig Within the AT and CG regions the force acting between two molecules is derived from the respective potentials.…”

“…In present work, in particular, we employ classical molecular dynamics within the context of the Adaptive Resolution Simulation approach (AdResS) 26,27 in its Grand Canonical version (GC-AdResS) [28][29][30] .…”