MCCCS Towhee (Aqvist ions)



    This section covers the Aqvist ion parameters as they are implemented into the towhee_ff_Aqvist file in the ForceFields directory. All of the Towhee atom types for the Aqvist 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 the positive ions in the first two columns of the periodic table. 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 positive 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 Aqvist 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 Aqvist ions Aqvist in Towhee
    The official force field name for Aqvist ions in Towhee is 'Aqvist'. Here I list all of the Aqvist 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.
    • 'Ba+2' : barium ion with a +2 charge
    • 'Ca+2' : calcium ion with a +2 charge
    • 'Cs+' : cesium ion with a +1 charge
    • 'K+' : potasium ion with a +1 charge
    • 'Li+' : lithium ion with a +1 charge
    • 'Mg+2' : magnesium ion with a +2 charge
    • 'Na+' : sodium ion with a +1 charge
    • 'Rb+' : rubidium ion with a +1 charge
    • 'Sr+2' : strontium ion with a +2 charge
Coulombic Interactions
    The Aqvist ions utilize point charges. All of the atoms in this force field are ions so the charge assignment is obvious.
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 Aqvist ions force field.
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Send comments to: Marcus G. Martin
Last updated: September 07, 2005