We propose 2 sets of intermolecular potentials for a united atom model of linear perfluorinated alkanes in their fluid states. Configurational-bias Monte Carlo simulations in the Gibbs ensemble have been carried out to determine the vapor-liquid phase equilibria for Cn F2n+2 with n = 5,6,1, 8, 10 and 16. Both sets of parameters yield critical temperatures which are in excellent agreement with experiment data. However, the critical densities are slightly too high for one model and slightly too low for the other. The saturated liquid densities agree with experiment to better than 5%. Variations of the critical properties with chain length show the correct scaling for both models.
Bibliographical noteFunding Information:
The part of this work carried out at UT/ORNL was sponsored in part by grant CTS-9613555 from the National Science Foundation. The work of HDC was supported by the Division of Chemical Sciences of the U.S. Department of Energy. The authors acknowledge the use of the SP2 computers in the Center for Computational Sciences at ORNL. ORNL is managed by Lockheed Martin Energy Research for the DOE under Contract No. DE-AC05-96OR22464. JIS would like to thank Ursula Röthlisberger for providing the torsional potential for model M. JIS acknowledges financial support from the Petroleum Research Fund, administered by the American Chemical Society (Grant No. 29960-AC9), and through a Camille and Henry Dreyfus New Faculty Award. A very generous amount of computer time was provided by the Minnesota Supercomputer Institute through the University of Minnesota-IBM Shared Research Project and NSF grant CDA-9502979.
- Critical point
- Gibbs ensemble monte carlo
- Molecular simulation
- Vapor-liquid phase equilibria