Molecular simulation of phase coexistence: Finite-size effects and determination of critical parameters for two- and three-dimensional Lennard-Jones fluids
- Cornell Univ., Ithaca, NY (United States)
The subject of this paper is the investigation of finite-size effects and the determination of critical parameters for a class of truncated Lennard-Jones potentials. Despite significant recent progress in our ability to model phase equilibria im multicomponent mixtures from direct molecular simulations, the accurate determination of critical parameters remains a difficult problem. Gibbs ensemble Monte Carlo simulations with systems of controlled linear system size are used to obtain the phase behavior in the near-critical region for two- and three-dimensional Lennard-Jones fluids with reduced cutoff radii of 2, 2.5, and 5. For the two-dimensional systems, crossover of the effective exponent for the width of the coexistence curve from mean field ({beta}={1/2}) in the immediate vicinity of the critical point to Ising-like ({beta} = 1/8) farther away is observed. Critical parameters determined by fitting the data that follow Ising-like behavior are in good agreement with literature values obtained with finite-size scaling methods. For three-dimensional systems, no crossover to mean field-type behavior was apparent. Extrapolated results for the critical parameters are consistent with literature estimates for similar fluids. For both two- and three-dimensional fluids, system size effects on the coexistence curves away from the critical point are small, normally within simulation statistical uncertainties.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 50768
- Report Number(s):
- CONF-940633--
- Journal Information:
- International Journal of Thermophysics, Journal Name: International Journal of Thermophysics Journal Issue: 6 Vol. 15; ISSN 0195-928X; ISSN IJTHDY
- Country of Publication:
- United States
- Language:
- English
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