Regensburg 2025 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 5: Statistical Physics: General

DY 5.4: Talk

Monday, March 17, 2025, 10:15–10:30, H47

Density Fluctuations, Solvation Thermodynamics and Coexistence Curves in Grand Canonical Molecular Dynamics Simulations — •Mauricio Sevilla, Luis A. Baptista, Kurt Kremer, and Robinson Cortes-Huerto — Max Planck Institute for Polymer Research

The physics of externally driven systems is a challenge as the complexity of the amount of effects involved, yet crucial to be understood as it is present in many biological systems. Aiming to build a computational method to deal with such situations, it is first needed to reproduce correctly the equilibrium statistics of open systems. However, open-boundary computational methods are scarce and often do not satisfy all the conditions imposed by reality. The system of interest (SoI) must be at thermodynamic and chemical equilibrium with an infinite reservoir of particles. The fluctuations of the SoI in equilibrium should sample the grand canonical ensemble. The local solvation thermodynamics, extremely sensitive to finite-size effects due to particle depletion, should be correctly described. The method should be robust enough to deal with phase transitions and coexistence conditions that might occur in the SoI. In this context, the adaptive resolution method (AdResS), where the system's atomistic and ideal gas representations coexist at constant thermodynamic and chemical equilibrium, emerges as a promising alternative. Indeed, in this talk, we demonstrate with prototypical liquid systems that AdResS, coupled with particle insertion/deletion steps, satisfies all these requirements, and it is thus a suitable method to perform simulations of open systems.

Keywords: Statistical Physics; Grand Canonical; Open systems; Externally Driven