Mixing Atomistic and Coarse-Grained MD

[Salman Zarrini]

Dear all,

I was wondering if it makes sense to mix all atoms (AA) and coarse-grained (CG) potentials in modeling a system including surfactant (in AA), epoxy resin (in CG) in water (in CG)? The CG potentials have been parameterized using iB and iBI approaches in VOTCA.

And;

As far as I noticed non of the examples in VOTCA's tutorial has assigned charge for the CG-beads so that the individual beads in your all examples are chargeless, I wonder if CG parametrization would be easier that way or there is any other reason for that? If I am not entirely wrong, to consider charge for each bead, one should sum up the atomic charges involved in that bead similar to bead's weight (<weights> 12 1 1 1 </weights>)? If so, is there something similar likes <charges> -0.18  0.06 0.06 0.06 </charges> for charge accordingly, in mapping scheme?

Thank you.

Salman Zarrini

Department of Chemical Engineering

Drexel University

[Christoph Junghans]

On Fri, May 10, 2019 at 4:22 PM Salman Zarrini <salman....@gmail.com> wrote:
>
>
> Dear all,
>
> I was wondering if it makes sense to mix all atoms (AA) and coarse-grained (CG) potentials in modeling a system including surfactant (in AA), epoxy resin (in CG) in water (in CG)? The CG potentials have been parameterized using iB and iBI approaches in VOTCA.

Mixing of different kind of models in simulation can be fairly
complicated, there is the adaptive resolution scheme (AdResS), which
does something along those lines.

>
> And;
>
> As far as I noticed non of the examples in VOTCA's tutorial has assigned charge for the CG-beads so that the individual beads in your all examples are chargeless, I wonder if CG parametrization would be easier that way or there is any other reason for that? If I am not entirely wrong, to consider charge for each bead, one should sum up the atomic charges involved in that bead similar to bead's weight (<weights> 12 1 1 1 </weights>)? If so, is there something similar likes <charges> -0.18 0.06 0.06 0.06 </charges> for charge accordingly, in mapping scheme?

Yes, charged system are bit more involves as one has to fit the long
range tail on the interaction to get the effective screening. Sikandar
did some work on that. Mapping of charges is currently not
implemented, but it wouldn't be hard to add.

Christoph

>
> Thank you.
>
> Salman Zarrini
> Department of Chemical Engineering
> Drexel University
>

> --
> You received this message because you are subscribed to the Google Groups "votca" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to votca+un...@googlegroups.com.
> To post to this group, send email to vo...@googlegroups.com.
> Visit this group at https://groups.google.com/group/votca.
> To view this discussion on the web visit https://groups.google.com/d/msgid/votca/86dfcb1b-7ad8-4c6d-b2d1-947933f1ee06%40googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.



--
Christoph Junghans
Web: http://www.compphys.de