MCCCS Towhee (Potter et al. 1997)



    This section covers the Potter et al. 1997 (Potter1997) force field as it is implemented into the towhee_ff_Potter1997 file in the ForceFields directory. This force field was designed to reproduce the vapour-liquid equilibria for three different fluoromethane molecules. Note that this is a Lennard-Jones force field that uses the 'LB plus manual' mixing rules, and therefore you will need to explicitly set some cross terms in towhee_input in order to use this force field as the authors intended. Any discrepencies (especially typos) from the published values are the sole responsibility of Marcus G. Martin, and I welcome feedback on how this implementation compares with other programs.
References for Potter et al. 1997 Typos and comments for Potter et al. 1997
  • Please note that you need to explicitly set the cross terms for H and F in towhee_input in order to properly reproduce their work. The cross terms for the H-F interactions should have a sigma of 2.3 Angstrom and an epsilon of 22.36 Kelvin. See the Potter_CF2H2 example for more information about how to set these cross terms.
Potter et al. 1997 in Towhee
    The official force field name for Potter et al. 1997 in Towhee is 'Potter1997'. Here is the list of atom names for use in the towhee_input file, along with a brief description. I created these names in order to distinguish between the different hydrogen and fluorine parmeters that are used depending upon the extent of methane fluorination. Please note that the capitalization and spacing pattern is important and must be followed exactly as listed here.
    • 'C' : Carbon in any of the fluoromethanes
    • 'F(2)' : Fluorine in CH2F2
    • 'F(3)' : Fluorine in CHF3
    • 'F(4)' : Fluorine in CF4
    • 'H(2)' : Hydrogen in CH2F2
    • 'H(1)' : Hydrogen in CHF3
Coulombic interactions
    This force field uses point charges and has been set up to assign the point charges using the bond increment method. The charges for bmim are assigned according to Table 1 of Potter et al. 1997.
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Send comments to: Marcus G. Martin
Last updated: April 27, 2006