The Barker-Fock model was used to study closed-loop phase diagrams. The model was solved by Bodegom and Meijer (Ref. 2) using the four-particle cluster variation method.
- J. A. Barker and W. Fock "Theory of upper and lower critical solution temperatures", Discussions of the Faraday Society 15 pp. 188 - 195 (1953)
- E. Bodegom and Paul H. E. Meijer "Coexistence and spinodal curves in directionally bonded liquids using the four-cluster approximation", Journal of Chemical Physics 80 pp. 1617-1624 (1984)