The Equation of State for Solution of Semiflexible Polymer Chains
  We formulate a self-consistent procedure for calculation of thermodynamic and structural properties of polymer solutions based on the Gaussian equivalent representation method (GER) for functional integrals calculation beyond the mean-field approximaton. We show that an equation of state, potential of mean force of interaction monomer-monomer, and persistent length should be defined self-consistently by solving of some system of coupled equation. 
Yu.A. Budkov, E.A. Nogovitsin and A.L. Kolesnikov
cond-mat.stat-mech