The penetrable square-well model: extensive versus non-extensive phases

Riccardo Fantoni (1) , Alexandr Malijevsky (2) , Andres Santos (3) , Achille Giacometti (4)

1 Institute of Theoretical Physics
2 Department of Physical Chemistry, Institute of Chemical Technology
3 Departamento de Fisica
4 Dipartimento di Scienze Molecolari e Nanosistemi

The phase diagram of the penetrable square-well fluid is investigated through Monte Carlo simulations of various nature. This model was proposed as the simplest possibility of combining bounded repulsions at short scale and short-range attractions. We prove that the model is thermodynamically stable for sufficiently low values of the penetrability parameter, and in this case the system behaves similarly to the square-well model. For larger penetration, there exists an intermediate region where the system is metastable, with well defined fluid-fluid and fluid-solid transitions, at finite size, but eventually becomes unstable in the thermodynamic limit. We characterize the unstable non-extensive phase appearing at high penetrability, where the system collapses into an isolated blob of a few clusters of many ovelapping particles each.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Riccardo Fantoni, Alexandr Malijevsky, Andres Santos, Achille Giacometti. The penetrable square-well model: extensive versus non-extensive phases. Molecular Physics, 2011, pp.1. ⟨10.1080/00268976.2011.597357⟩. ⟨hal-00719817⟩