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MCCCS Towhee (Wielopolski and Smith 1985)

 

Overview
    This section covers the two versions of the Wielopolski and Smith 1985 ethylene oxide models as they are implemented into the Towhee code. All of the Towhee atom types for the Wielopolski and Smith 1985 force field are listed, along with a short description of their meanings. Note that Wielopolski and Smith 1985 is a Lennard-Jones force field and can only be combined with other 'Lennard-Jones' force fields. Any discrepencies (especially typos) from the published force field values are the sole responsibility of Marcus G. Martin, and I welcome feedback on how this implementation compares with other programs.

     

References for Wielopolski and Smith 1985 Typos and comments for Wielopolski and Smith 1985 Wielopolski and Smith 1985 in Towhee
    The official force field name for Wielopolski and Smith in Towhee is 'Wielop1985' and the file name is towhee_ff_Wielop1985 in the ForceFields directory. An undocumented version of this forcefield was available prior to Towee version 7.1.0, but it contained errors in the rigid bond angles and was therefore unusable. Below is a list of all the atom names for use in the towhee_input file, along with a brief description taken from the Wielopolski and Smith 1985 paper. Please note that the capitalization and spacing pattern is important and must be followed exactly as listed here.
    • 'CH2:A' : united sp3 carbon with two hydrogens in ethylene oxide, model A.
    • 'CH2:B' : united sp3 carbon with two hydrogens in ethylene oxide, model B.
    • 'O:A' : oxygen in ethylene oxide, model A.
    • 'O:B' : oxygen in ethylene oxide, model B.
Coulombic interactions
    Wielopolski and Smith 1985 uses atom-centered point charges to represent the electrostatic interactions with a charge of -0.32016 on the oxygen and 0.1608 on the two carbons in ethylene oxide. Here I list the bond increments using the bond names listed above. The value of the bond increment is added to the first atom listed and subtracted from the second atom listed.
    • CH2:A - O:A: 0.1608
    • CH2:B - O:B: 0.1608
Improper torsions
    There are no improper torsions in this model.
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Send comments to: Marcus G. Martin
Last updated:July 24, 2014