Uncertainty quantification and propagation of errors of the Lennard-Jones 12-6 parameters for n-alkanes

Authors

Richard A. Messerly, Brigham Young University
Thomas A. Knotts IV, Brigham Young University
W Vincent Wilding, Brigham Young University

Keywords

Molecular simulations, Phase transitions, Thermodynamic states and processes, Thermodynamic properties, Chemical elements, Intermolecular forces, Organic compounds, Gaussian processes, Monte Carlo methods, Statistical analysis

Abstract

Molecular simulation has the ability to predict various physical properties that are difficult to obtain experimentally. For example, we implement molecular simulation to predict the critical constants (i.e., critical temperature, critical density, critical pressure, and critical compressibility factor) for large n-alkanes that thermally decompose experimentally (as large as C₄₈). Historically, molecular simulation has been viewed as a tool that is limited to providing qualitative insight. One key reason for this perceived weakness in molecular simulation is the difficulty to quantify the uncertainty in the results. This is because molecular simulations have many sources of uncertainty that propagate and are difficult to quantify. We investigate one of the most important sources of uncertainty, namely, the intermolecular force field parameters. Specifically, we quantify the uncertainty in the Lennard-Jones (LJ) 12-6 parameters for the CH₄, CH₃, and CH₂ united-atom interaction sites. We then demonstrate how the uncertainties in the parameters lead to uncertainties in the saturated liquid density and critical constant values obtained from Gibbs Ensemble Monte Carlo simulation. Our results suggest that the uncertainties attributed to the LJ 12-6 parameters are small enough that quantitatively useful estimates of the saturated liquid density and the critical constants can be obtained from molecular simulation.

Original Publication Citation

R. A. Messerly, T. A. Knotts IV, and W. V. Wilding. Uncertainty Quanti cation and Propagation of Errors of the Lennard-Jones 12-6 Parameters for n-Alkanes, J. Chem. Phys., 146, 194110 (2017).

BYU ScholarsArchive Citation

Messerly, Richard A.; Knotts, Thomas A. IV; and Wilding, W Vincent, "Uncertainty quantification and propagation of errors of the Lennard-Jones 12-6 parameters for n-alkanes" (2017). Faculty Publications. 7698.
https://scholarsarchive.byu.edu/facpub/7698

Document Type

Peer-Reviewed Article

Publication Date

2017-05-19

Publisher

American Institute of Physics

Language

English

College

Ira A. Fulton College of Engineering

Department

Chemical Engineering

University Standing at Time of Publication

Full Professor

Copyright Use Information

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