Issue 30, 2023

Phase behaviour of coarse-grained fluids

Abstract

Soft condensed matter structures often challenge us with complex many-body phenomena governed by collective modes spanning wide spatial and temporal domains. In order to successfully tackle such problems, mesoscopic coarse-grained (CG) statistical models are being developed, providing a dramatic reduction in computational complexity. CG models provide an intermediate step in the complex statistical framework of linking the thermodynamics of condensed phases with the properties of their constituent atoms and molecules. These allow us to offload part of the problem to the CG model itself and reformulate the remainder in terms of reduced CG phase space. However, such exchange of pawns to chess pieces, or ‘Hamiltonian renormalization’, is a radical step and the thermodynamics of the primary atomic and CG models could be quite distinct. Here, we present a comprehensive study of the phase diagram including binodal and interfacial properties of a dissipative particle dynamics (DPD) model, extended to include finite-range attraction to support the liquid–gas equilibrium. Despite the similarities with the atomic model potentials, its phase envelope is markedly different featuring several anomalies such as an unusually broad liquid range, change in concavity of the liquid coexistence branch with variation of the model parameters, volume contraction on fusion, temperature of maximum density in the liquid phase and negative thermal expansion in the solid phase. These results provide new insight into the connection between simple potential models and complex emergent condensed matter phenomena.

Graphical abstract: Phase behaviour of coarse-grained fluids

Article information

Article type
Paper
Submitted
26 Jun 2023
Accepted
10 Jul 2023
First published
11 Jul 2023
This article is Open Access
Creative Commons BY license

Soft Matter, 2023,19, 5824-5834

Phase behaviour of coarse-grained fluids

V. P. Sokhan, M. A. Seaton and I. T. Todorov, Soft Matter, 2023, 19, 5824 DOI: 10.1039/D3SM00835E

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