Weeks-Chandler-Andersen perturbation theory

From SklogWiki
Jump to: navigation, search

The Weeks-Chandler-Andersen perturbation theory [1] is based on the following decomposition of the intermolecular pair potential (in particular, the Lennard-Jones potential):

The reference system pair potential is given by (Eq, 4):

\[ \Phi_{\rm repulsive} (r) = \left\{ \begin{array}{ll} \Phi_{\rm LJ}(r) + \epsilon & {\rm if} \; r < 2^{1/6}\sigma \\ 0 & {\rm if} \; r \ge 2^{1/6}\sigma \end{array} \right. \]

and the perturbation potential is given by (Eq, 5 Ref. 1):

\[ \Phi_{\rm attractive} (r) = \left\{ \begin{array}{ll} -\epsilon & {\rm if} \; r < 2^{1/6}\sigma \\ \Phi_{\rm LJ}(r) & {\rm if} \; r \ge 2^{1/6}\sigma \end{array} \right. \]

Ben-Amotz-Stell reformulation[edit]



The repulsive component of the WCA decomposition has been used as a model for colloids [3].


  1. John D. Weeks, David Chandler and Hans C. Andersen "Role of Repulsive Forces in Determining the Equilibrium Structure of Simple Liquids", Journal of Chemical Physics 54 pp. 5237-5247 (1971)
  2. Dor Ben-Amotz and George Stell "Reformulation of Weeks-Chandler-Andersen Perturbation Theory Directly in Terms of a Hard-Sphere Reference System", Journal of Physical Chemistry B 108 pp. 6877-6882 (2004)
  3. L. Filion, R. Ni, D. Frenkel, and M. Dijkstra "Simulation of nucleation in almost hard-sphere colloids: The discrepancy between experiment and simulation persists", Journal of Chemical Physics 134 134901 (2011)