MCCCS Towhee (Lybrand-Ghosh-McCammon ions)



    This section covers the Lybrand-Ghosh-McCammon (LGM) ion parameters as they are implemented into the towhee_ff_LGM file in the ForceFields directory. All of the Towhee atom types for the LGM ion force field are listed, along with a short description of their meanings. This is not really a comphrehensive stand-alone force field, but is instead a collection of parameters for some negative halide ions. Ion parameters are sometimes hard to come by in the literature so I have included these parameters for use in conjunction with other force fields (as a simulation of only negative ions is not very interesting). Note that these are Lennard-Jones (12-6) parameters and can only be combined with other Lennard-Jones (12-6) force fields. Any discrepencies (especially typos) from the published LGM 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 Lybrand-Ghosh-McCammon ions Lybrand-Ghosh-McCammon in Towhee
    The official force field name for Lybrand-Ghosh-McCammon in Towhee is 'LGM'. Here I list all of the LGM atom names for use in the towhee_input file, along with a brief description (although the meaning of the atom names should be obvious). Please note that the capitalization and spacing pattern is important and must be followed exactly as listed here.
    • 'Br-' : bromine ion with a -1 charge
    • 'Cl-' : chlorine ion with a -1 charge
Coulombic interactions
    Atom centered point charges are used to represent the electrostatic interactions. As this is a force field for ions, the charge assignments are straight forward.
    • 'Br-' : -1.0
    • 'Cl-' : -1.0
Improper torsions
    This force field only has parameters for ions so there are no improper torsions.
    This force field only has parameters for ions, and while you are welcome to use them with another protein force field, there are no amino acids in the LGM ions force field.
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Send comments to: Marcus G. Martin
Last updated: September 07, 2005