Editing Square shoulder model

The '''square shoulder model''' is given by <ref>[http://dx.doi.org/10.1063/1.433373 J. M. Kincaid, G. Stell and E. Goldmark "Isostructural phase transitions due to core collapse. II. A three-dimensional model with a solid–solid critical point", Journal of Chemical Physics '''65''' pp. 2172-2179 (1976)]</ref>

:<math>
\Phi_{12}\left( r \right) = 
\left\{ \begin{array}{ccc}
\infty & ; & r < \sigma \\
\epsilon & ; &\sigma \le r < \lambda \sigma \\
0         & ; & r \ge \lambda \sigma \end{array} \right.
</math>

where <math>\Phi_{12}(r)</math> is the [[intermolecular pair potential]], <math>\epsilon</math> is the height of the shoulder, <math>r</math> is the distance between site 1 and site 2  <math>r := |\mathbf{r}_1 - \mathbf{r}_2|</math>, &sigma; is the hard diameter
and &lambda; &gt; 1.
==Direct correlation function==
The [[direct correlation function]] <ref>[http://dx.doi.org/10.1080/00268970903539592 I. Guillén-Escamilla,  E. Schöll-Paschinger and R. Castañeda-Priego "A parametrisation of the direct correlation function for the square-shoulder fluid", Molecular Physics '''108''' pp. 141-150 (2010)]</ref>
==Equation of State==
<ref>[http://dx.doi.org/10.1088/0953-8984/11/50/308  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)]</ref>
==References==
<references/>
'''Related reading'''
*[http://dx.doi.org/10.1088/0953-8984/9/1/001 A R Denton and H Löwen  "Isostructural solid - solid transitions in square-shoulder systems", Journal of Physics: Condensed Matter '''9''' pp. L1-L5  (1997)]
*[http://dx.doi.org/10.1088/0953-8984/9/2/006  Peter Bolhuis and Daan Frenkel "Isostructural solid - solid transitions in systems with a repulsive `shoulder' potential", Journal of Physics: Condensed Matter '''9''' pp. 381-387  (1997)]
*[http://dx.doi.org/10.1063/1.3006065  Gernot J. Pauschenwein and Gerhard Kahl "Zero temperature phase diagram of the square-shoulder system", Journal of Chemical Physics '''129''' 174107 (2008)]
*[http://dx.doi.org/10.1063/1.3265984 Shiqi Zhou and J. R. Solana "Inquiry into thermodynamic behavior of hard sphere plus repulsive barrier of finite height", Journal of Chemical Physics '''131''' 204503 (2009)]
*[http://dx.doi.org/10.1080/00268976.2011.562472 S. B. Yuste, A. Santos and M. López de Haro "Structure of the square-shoulder fluid", Molecular Physics '''109''' pp. 987-995 (2011)]


[[Category: Models]]