# Square shoulder + square well model

The **Square shoulder + square well** model consists, as its name suggests, of a combination of the square shoulder model and the square well model. The model is given by

where is the intermolecular pair potential, and are the well *depths*, is the distance between site 1 and site 2 where , σ is the hard core diameter
and

## Liquid-liquid transition[edit]

For certain parameter sets the square shoulder + square well model has a liquid-liquid transition along with a corresponding liquid-liquid critical point
^{[1]}
^{[2]}
^{[3]}
^{[4]}.

## See also[edit]

## References[edit]

- ↑ Giancarlo Franzese, Gianpietro Malescio, Anna Skibinsky, Sergey V. Buldyrev, and H. Eugene Stanley "Generic mechanism for generating a liquid-liquid phase transition", Nature
**409**pp. 692-695 (2001) - ↑ Giancarlo Franzese, Gianpietro Malescio, Anna Skibinsky, Sergey V. Buldyrev, and H. Eugene Stanley, "Metstable liquid-liquid phase transition in a single-component system with only one crystal phase and no density anomaly", Physical Review E
**66**051206 (2002) - ↑ Anna Skibinsky, Sergey V. Buldyrev, Giancarlo Franzese, Gianpietro Malescio, and H. Eugene Stanley, "Liquid-liquid phase transitions for soft-core attractive potentials", Physical Review E
**69**061206 (2004) - ↑ Gianpietro Malescio, Giancarlo Franzese, Anna Skibinsky, Sergey V. Buldyrev, and H. Eugene Stanley, "Liquid-liquid phase transition for an attractive isotropic potential with wide repulsive range", Physical Review E
**71**061504 (2005)

- Related reading

- Andreas Lang, Gerhard Kahl, Christos N Likos, Hartmut Löwen and Martin Watzlawek "Structure and thermodynamics of square-well and square-shoulder fluids", Journal of Physics: Condensed Matter
**11**pp. 10143-10161 (1999) - W. Rzysko, O. Pizio, A. Patrykiejew, and S. Sokolowski "Phase diagram of a square-shoulder, square-well fluid revisited", Journal of Chemical Physics
**129**124502 (2008) - Shiqi Zhou, A. Lajovic, and A. Jamnik "Local structures of fluid with discrete spherical potential: Theory and grand canonical ensemble Monte Carlo simulation", Journal of Chemical Physics
**129**124503 (2008)