Calculation of real gas pressures using modified functions of   probability distributions
  We have improved the procedure for calculating distribution functions and the thermal equation of state for real gases by introducing modified functions of probability distributions into the gas phase state sum. Calculation of real gas pressure and the grand canonical partition function using the improved procedure demonstrate that numerical difficulties arising from a large number of state variables can be circumvented. We have also calculated real gas isotherms and probability of vaporization in phase equilibrium. 
A.I. Liutuy, L.N. Glushko, A.A. Ostapenko
cond-mat.stat-mech