Phase diagram of a double-occupancy cell model of a fluid with Curie-Weiss interaction
Abstract
A double-occupancy cell model of a fluid with Curie-Weiss interaction is studied. First, we show that the model is isomorphic to the Blume-Capel model on a complete graph through a simple transformation from spin to occupancy variables. We then investigate its phase behavior within the grand-canonical ensemble using a combination of analytical and numerical methods. Despite its simplicity, the model exhibits a remarkably rich thermodynamic behavior depending on the ratio between the local repulsive and global attractive interactions. We identify the regimes characterized by a single critical point, two distinct critical points, tricritical behavior, and triple-point formation. For sufficiently strong repulsion, the system possesses three fluid phases of different densities, leading to both gas-liquid and liquid-liquid coexistence. The locations of the critical, tricritical, and triple points are determined, and the corresponding phase diagrams are constructed. These results demonstrate that the competition between double-occupancy repulsion and long-range attraction is sufficient to generate a complex phase behavior in a minimal multiple-occupancy lattice-gas-like model.
Versions
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BibTeX
@misc{romanik2026phase,
title = {{Phase diagram of a double-occupancy cell model of a fluid with Curie-Weiss interaction}},
author = {R. V. Romanik and O. A. Dobush and M. P. Kozlovskii and I. V. Pylyuk and M. A. Shpot},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.01009},
eprint = {2607.01009},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.01009},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Phase diagram of a double-occupancy cell model of a fluid with Curie-Weiss interaction
AU - R. V. Romanik
AU - O. A. Dobush
AU - M. P. Kozlovskii
AU - I. V. Pylyuk
AU - M. A. Shpot
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2607.01009
UR - https://arxiv.org/abs/2607.01009
AB - A double-occupancy cell model of a fluid with Curie-Weiss interaction is studied. First, we show that the model is isomorphic to the Blume-Capel model on a complete graph through a simple transformation from spin to occupancy variables. We then investigate its phase behavior within the grand-canonical ensemble using a combination of analytical and numerical methods. Despite its simplicity, the model exhibits a remarkably rich thermodynamic behavior depending on the ratio between the local repulsive and global attractive interactions. We identify the regimes characterized by a single critical point, two distinct critical points, tricritical behavior, and triple-point formation. For sufficiently strong repulsion, the system possesses three fluid phases of different densities, leading to both gas-liquid and liquid-liquid coexistence. The locations of the critical, tricritical, and triple points are determined, and the corresponding phase diagrams are constructed. These results demonstrate that the competition between double-occupancy repulsion and long-range attraction is sufficient to generate a complex phase behavior in a minimal multiple-occupancy lattice-gas-like model.
ER -