MCCCS Towhee (Kramer-Farragher-van Beest-van Santen)



    This section covers the Kramer-Farragher-van Beest-van Santen (KFvBvS) force field as it is implemented into the towhee_ff_KFvBvS file in the ForceFields directory. All of the Towhee atom types for the KFvBvS force field are listed, along with a short description of their meanings. The KFvBvS force field uses the exponential-6 potential type and therefore must also use explicit combining rules. It therefore cannot be combined with other 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 KFvBvS
    This force field comes from the work of Kramer, Farragher, van Beest, and van Santen. I created the name for this force field from the initials of the last names of the authors. The parameters were taken from the mixed SCF empirical force field listed in
KFvBvS in Towhee
    The official force field name for these parameters is either 'KFvBvS'. Here I list all of the KFvBvS atom names for use in the towhee_input file, along with a brief description of what atoms we are talking about. This force field is intended for use with silacious materials (zeolites, silica, etc.). For some reason they did not include repulsive potentials between many of the atoms and Cl. Thus, Cl can only be used in combination with other negative ions, or with Na. Please note that the capitalization and spacing pattern is important and must be followed exactly as listed here.
    • 'Al' : aluminum
    • 'Cl' : chlorine
    • 'Na' : sodium
    • 'O' : oxygen
    • 'P' : phosphorous
    • 'Si' : silicon
Coulombic interactions
    Atom centered point charges are used to represent the electrostatic interactions. Below is a list of charges taken from the mixed SCF empirical force field in Kramer et al. 1991
  • 'Al' : 1.4
  • 'Cl' : -1.0
  • 'Na' : 1.0
  • 'O' : -1.2
  • 'P' : 3.4
  • 'Si' : 2.4
Improper torsions
    There are no improper torsions in this force field.
    The KFvBvS force field is designed for zeolites and is not suited for proteins.
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Send comments to: Marcus G. Martin
Last updated: September 07, 2005