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MCCCS Towhee (Alavi et al. 2005)

 

 

Overview
    This section covers the Alavi et al. 2005 (Alavi2005) force field as it is implemented into the towhee_ff_Alavi2005 file in the ForceFields directory. All of the Towhee atom types for this force field are listed, along with a short description of their meanings. Note that this a Lennard-Jones (12-6) force field and can only be combined with other Lennard-Jones (12-6) force fields. Any discrepencies (especially typos) from the published values are the sole responsibility of Marcus G. Martin, and I welcome feedback on how this implementation compares with other programs.
References for Alavi2005
    This force field was published in a single paper where it was used along with the SPC/E force field for water.
Alavi et al. 2005 in Towhee
    The official force field name for Alavi et al. 2005 in Towhee is 'Alavi2005'. Here I list all of the atom names for use in the towhee_input file, along with a brief description. I created these atom names in order to work with the molecule assembler. This force field was designed to work with the SPC/E water model. This force field uses a three site model for H2 as described below. Please note that the capitalization and spacing pattern is important and must be followed exactly as listed here.
    • 'H2-com' : the center of mass of an H2 molecule. This atom type has no mass itself and should be bonded to 2 H2-end sites.
    • 'H2-end' : hydrogen atom in H2. This atom type represents the mass point for each hydrogen atom and should be bonded to the H2-com site.
Coulombic interactions
    Alavi2005 assigns a point charge to the H2 mass sites and also to the center of mass location. The bond increment method is implemented for this forcefield and can be used to automatically assign appropriate charges. Please see the inpstyle 2 documentation for further information on enabling this option. 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.
    • H2-end - H2-com: 0.4932

 


Send comments to: Marcus G. Martin
Last updated: September 26, 2005