Optimised Mie potentials for phase equilibria: application to alkynes

ABSTRACT

A transferable united-atom force field, based on Mie potentials, is presented for alkynes. The performance of the optimised Mie potential parameters is assessed for 1-alkynes and 2-alkynes using grand canonical histogram-reweighting Monte Carlo simulations. For each compound, vapour–liquid coexistence curves, vapour pressures, heats of vapourisation, critical properties and normal boiling points are predicted and compared to experiment. Experimental saturated liquid densities are reproduced to within 2% average absolute deviation (AAD), except for 1-hexyne, which are reproduced with 3% AAD. Experimental saturated vapour pressures are reproduced to within 3% AAD, except for 1-pentyne, 2-pentyne and 2-hexyne, where deviations from experiment of up to 20% AAD were observed. Binary phase diagrams, predicted from Gibbs ensemble Monte Carlo simulations, for propane + propyne, propene + propyne and propadiene + propyne, are in close agreement with experiment.

KEYWORDS:

• Monte Carlo
• alkyne
• vapour–liquid
• force field

Acknowledgments

Funding from the National Science Foundation ACI-1148168 is gratefully acknowledged. We are grateful to Prof. Jadran Vrabec and Prof. J. Richard Elliott for providing tabulated numerical data for the 2CLJQ and SPEAD models, respectively, and William Zygmunt for useful discussions. Some of the computations in this work were performed with resources from the Grid Computing initiative at Wayne State University.

Disclosure statement

The authors declare no competing financial interest.

Additional information

Funding

This work was supported by the National Science Foundation [grant number ACI-1148168; Division of Advanced Cyberinfrastructure.]