Resummed thermodynamic perturbation theory for bond cooperativity in   associating fluids with small bond angles: Effects of steric hindrance and   ring formation
  In this paper we develop a thermodynamic perturbation theory for two site associating fluids which exhibit bond cooperativity. We include both steric hindrance and ring formation such that the equation of state is bond angle dependent. Here the bond angle is the angle separating the centers of the two association sites. As a test, new Monte Carlo simulations are performed, and the theory is found to accurately predict the internal energy as well as the distribution of associated clusters as a function of bond angle and bond cooperativity. 
B. D. Marshall, Amin Haghmoradi, W. G. Chapman
cond-mat.soft cond-mat.stat-mech