A force-field description of short-range repulsions for high density alkane molecular dynamics simulations

Joseph M. Hayes, James C. Greer, David A. Morton-Blake

Research output: Journal PublicationArticlepeer-review

25 Citations (Scopus)


The use of Buckingham (exp-6) van der Waals potentials in molecular dynamics (MD) simulations can quite successfully reproduce experimental thermodynamic data at low densities. However, they are less successful in producing a description of the repulsive regions of the potential energy surface (PES) that is in accord with the results of high-level ab initio computations. We show that Morse potentials can be parameterized to give excellent fits to both the attractive and repulsive regions of the PES. The best set of alkane van der Waals Morse function parameters reported to date for the description of nonbond repulsive interactions is presented, as determined by comparison with both ab initio and experimental results. C⋯ C, H⋯ H and C⋯ H atom-pair potentials employing parameter sets based on the use of the geometric mean in the fitting procedure are found to be portable from methane to n-butane. Fitting to a combination of methane dimer interaction energies and forces from ab initio calculations yields parameter sets whose performance is superior to those determined from the interaction energies alone. Used in MD simulations, our newly developed parameter sets predict thermodynamic functions that show better agreement with experiment than those based on parameter sets in common use.

Original languageEnglish
Pages (from-to)1953-1966
Number of pages14
JournalJournal of Computational Chemistry
Issue number16
Publication statusPublished - Dec 2004
Externally publishedYes


  • Alkanes
  • Forcefields
  • High pressure
  • Nonbond interactions
  • Van der waals

ASJC Scopus subject areas

  • General Chemistry
  • Computational Mathematics


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