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1298 Views 1 Reply Latest reply: Apr 7, 2012 1:37 AM by reiniera RSS
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Apr 3, 2012 10:36 AM

Electrostatic interactions in DPD

I have a question regarding the DPD forcefield in Mesocite.

I have a small amount of charged beads in my meso-system. Is it possible to incorporate electrostatic interactions in the DPD forcefield of Mesocite?

Is the DPD cutoff distance defined in DPD forcefield code just for vdw interactions or all non bond interactions?

  • reiniera Accelrys 495 posts since
    Oct 31, 2006
    Currently Being Moderated
    Apr 7, 2012 1:37 AM (in response to sina)
    Electrostatic interactions in DPD

    Hi Sina,

     

    It is possible, in principle, to use electrostatic interactions in Mesocite DPD, with either Bead based or Ewald summation methods. To enable electrostatics, open your force field, and click More... on the Interactions tab, then tick "Use electrostatics". You can now select Electrostatics on the Interactions tab, with a choice of either Coulomb (1/r) or Shielded (1/r^2) for the functional form.

     

    You may want to exclude 1-2 and 1-3 interactions (if there are bonds connecting charged beads), but be aware that this will also apply to van der Waals interactions. Likewise the cutoff distance (when using Bead based summation) is the same for both interactions. It is best to use Ewald for Coulomb, and Bead based for Shielded potentials. Partial charges can be applied to beads using the Property Explorer or via Build > Modify Charges.

     

    Note that all this is based on point charges, whereas a spread-out charge distribution may be more realistic for beads. However this requires a Poisson-Boltzmann solver (e.g. here) which is not available in Mesocite at present.

     

    Hope this helps,

    Reinier

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