Liquid-liquid coexistence in the phase diagram of a fluid confined in fractal porous materialsV. De Grandis, P. Gallo and M. Rovere
Dipartimento di Fisica, Università "Roma Tre" and Democritos National Simulation Center, INFM-CNR Via della Vasca Navale 84, 00146 Roma, Italy
received 18 May 2006; accepted in final form 31 July 2006
published online 23 August 2006
Multicanonical ensemble sampling simulations have been performed to calculate the phase diagram of a Lennard-Jones fluid embedded in a fractal random matrix generated through diffusion-limited cluster aggregation. The study of the system at increasing size and constant porosity shows that the results are independent of the matrix realization but not of the size effects. A gas-liquid transition shifted with respect to bulk is found. On growing the size of the system on the high-density side of the gas-liquid coexistence curve there appears a second coexistence region between two liquid phases. These two phases are characterized by a different behaviour of the local density inside the interconnected porous structure at the same temperature and chemical potential.
61.20.Ja - Computer simulation of liquid structure.
61.20.-p - Structure of liquids.
64.70.Fx - Liquid-vapor transitions.
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