Improved reference system for the corrected rigid spheres equation of state model

The Corrected Rigid Spheres (CRIS) equation of state (EOS) model [Kerley, J. Chem. Phys. 73, 469 (1980); 73, 478 (1980); 73, 487 (1980)], developed from fluid perturbation theory using a hard sphere reference system, has been successfully used to calculate the EOS of many materials, including gases...

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Bibliographic Details
Published in:Journal of applied physics 2020-08, Vol.128 (5)
Main Authors: Cowen, B. J., Carpenter, J. H.
Format: Article
Language:English
Subjects:
Applied physics
Argon
Critical point
Distribution functions
Domes
Equations of state
Perturbation theory
Radial distribution
Reference systems
Spheres
Vapors
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Summary:The Corrected Rigid Spheres (CRIS) equation of state (EOS) model [Kerley, J. Chem. Phys. 73, 469 (1980); 73, 478 (1980); 73, 487 (1980)], developed from fluid perturbation theory using a hard sphere reference system, has been successfully used to calculate the EOS of many materials, including gases and metals. The radial distribution function (RDF) plays a pivotal role in choosing the sphere diameter, through a variational principle, as well as the thermodynamic response. Despite its success, the CRIS model has some shortcomings in that it predicts too large a temperature for liquid-vapor critical points, can break down at large compression, and is computationally expensive. We first demonstrate that an improved analytic representation of the hard sphere RDF does not alleviate these issues. Relaxing the strict adherence of the RDF to hard spheres allows an accurate fit to the isotherms and vapor dome of the Lennard-Jones fluid using an arbitrary reference system. The second order correction is eliminated, limiting the breakdown at large compression and significantly reducing the computation cost. The transferability of the new model to real systems is demonstrated on argon, with an improved vapor dome compared to the original CRIS model.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0013080