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
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
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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