Abstract

GUILLEN-ESCAMILLA, I.; MENDEZ-BERMUDEZ, J. G.; MIXTECO-SANCHEZ, J. C.  and  MENDEZ-MALDONADO, G. A.. Microphase and macrophase separations in discrete potential fluids. Rev. mex. fis. [online]. 2022, vol.68, n.5, e50502.  Epub Feb 17, 2023. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.68.050502.

In this paper, we study the liquid-vapor phase diagram and structural properties of discrete potential fluids using integral equations theory and Monte Carlo simulations in Gibbs ensemble. For this purpose, we considered three discrete fluids, namely, square well, square well-barrier, and square well-barrier-well. They represent simple models of fluids with competing interactions that exhibit rich microscopic and macroscopic phase behavior, depending on the strength and range of attractions and repulsions in the potential. Here, we emphasized a structural behavior near the liquid-vapor coexistence. For the square well-barrier fluid, we observed a possible scenario of a microscopic phase separation associated with a cluster-like formation near the critical region, which could be interpreted as a frustration mechanism of the liquid-vapor transition when either the strength or the range of repulsion increases. This microscopic-like separation can be inhibited by suppressing the repulsion or by adding an extra well to the interaction potential. However, for the square well fluid with long-range potential, we found evidence of a microscopic aggregation driven solely by attractions.

Keywords : Discrete potential fluids; phase transitions; cluster formation.

        · text in English     · English ( pdf )