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Coexistence calculation using the Isothermal-Isochoric Integration Method


Seyed M. Razavi, Richard A. Messerly, J. R. Elliott


In this work, an isothermal-isochoric integration (ITIC) method is proposed and tested as a viable method for vapor pressure calculation by molecular simulation. Several tests were carried out to validate the method which resulted in less than 1 % deviation from NIST data for reduced temperatures of less than 0.85. While consistency is achieved between the ITIC method, Gibbs Ensemble Monte Carlo (GEMC) method, and Grand Canonical Monte Carlo (GCMC) method when reduced temperatures of 0.6-0.85, the ITIC method is much more effective for vapor pressure calculations at reduced temperatures of 0.45-0.6, where relative deviations from experimental data are often quite large but important for practical applications. It is shown that computational eciency for the complete temperature range is often served best by applying the ITIC method for the entire temperature range rather than applying Monte Carlo (MC) methods for part of the range. Furthermore, the ITIC method lends itself to application with molecular dynamics (MD) as well as MC, advancing the prospect of simulation results that are quantitatively consistent across software platforms.
Fluid Phase Equilibria


Vapor Pressure, Vapor Liquid Equilibria, Phase Diagram, Liquid Density


Razavi, S. , Messerly, R. and Elliott, J. (1970), Coexistence calculation using the Isothermal-Isochoric Integration Method, Fluid Phase Equilibria (Accessed April 19, 2024)
Created September 22, 2018, Updated September 21, 2018