Keywords
Ab-initio methods, Molecular dynamics, Phase transitions, Equations of state, Thermodynamic states and processes, Interatomic potentials, Intermolecular potentials, Organic compounds, Chemical bonding, Statistical mechanics
Abstract
Two-phase molecular dynamics simulations employing a Monte Carlo volume sampling method were performed using an ab initio based force field model parameterized to reproduce quantum-mechanical dimer energies for methanol and 1-propanol at temperatures approaching the critical temperature. The intermolecular potential models were used to obtain the binodal vapor-liquid phase dome at temperatures to within about 10 K of the critical temperature. The efficacy of two all-atom, site-site pair potential models, developed solely from the energy landscape obtained from high-level ab initio pair interactions, was tested for the first time. The first model was regressed from the ab initio landscape without point charges using a modified Morse potential to model the complete interactions; the second model included point charges to separate Coulombic and dispersion interactions. Both models produced equivalent phase domes and critical loci. The model results for the critical temperature, density, and pressure, in addition to the sub-critical equilibrium vapor and liquid densities and vapor pressures, are compared to experimental data. The model's critical temperature for methanol is 77 K too high while that for 1-propanol is 80 K too low, but the critical densities are in good agreement. These differences are likely attributable to the lack of multi-body interactions in the true pair potential models used here.
Original Publication Citation
Sonal Patel, W. Vincent Wilding, Richard L. Rowley; Critical and phase-equilibrium properties of an ab initio based potential model of methanol and 1-propanol using two-phase molecular dynamics simulations. J. Chem. Phys. 21 December 2011; 135 (23): 234514. https://doi.org/10.1063/1.3670013
BYU ScholarsArchive Citation
Patel, Sonal; Wilding, W. Vincent; and Rowley, Richard L., "Critical and phase-equilibrium properties of an ab initio based potential model of methanol and 1-propanol using two-phase molecular dynamics simulations" (2011). Faculty Publications. 7820.
https://scholarsarchive.byu.edu/facpub/7820
Document Type
Peer-Reviewed Article
Publication Date
2011-12-21
Publisher
American Institute of Physics
Language
English
College
Ira A. Fulton College of Engineering
Department
Chemical Engineering
Copyright Status
© 2011 American Institute of Physics
Copyright Use Information
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