[DFTB-Plus-User] regarding forces module

[Sharma SRK Chaitanya Yamijala]

Dear Balint,

Thank you very much for the help.

Sharma.





--------------------------------------------------------------------
Sharma
http://www.chem.rochester.edu/groups/huo/people/


On Fri, Aug 25, 2017 at 7:35 AM, Bálint Aradi <aradi at uni-bremen.de> wrote:

> Dear Sharma,
>
> > I read the comments above the loop. But, it is not clear to me from
> > these comments that why the first loop in the derivative_nonSCC routine,
> > i.e.,
> >
> >           do ii = 1, 3
> >             deriv(ii,iAtom1) = deriv(ii,iAtom1) &
> >                 &+ sum(sqrDMTmp(1:nOrb2,1:nOrb1)&
> >                 &* 2.0_dp*hPrimeTmp(1:nOrb2,1:nOrb1,ii)) &
> >                 &- sum(sqrEDMTmp(1:nOrb2,1:nOrb1)&
> >                 &* 2.0_dp*sPrimeTmp(1:nOrb2,1:nOrb1,ii))
> >           end do
> >
> > is not sufficient to describe the force on iAtom1?
>
> The loop is not sufficient, as our neighbor list over which the outer
> loop (do iNeigh = 1, ...) runs only contains half of the neighborship
> relations. (For each atom, only neighbors are recorded, which have an
> index higher than the atom itself.) Therefore, you have to make sure,
> you sum up the contribution for the missing neighbors.
>
> > P. S.: May I also know, why derivative_nonSCC is separately made public
> > despite its availability through the derivative_shift interface?
>
> That seems to be inconsistent coding style at the first glance, indeed.
> We'll fix that.
>
>   Cheers,
>
>    Bálint
>
> --
> Dr. Bálint Aradi
> Bremen Center for Computational Materials Science, University of Bremen
> http://www.bccms.uni-bremen.de/cms/people/b-aradi/
>
>
>
>
>
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