[DFTB-Plus-User] consistency check for "makeDensityMatrix"

[Ben Hourahine]

Just replied off list.

But in case anyone else is interested, DFTB+ uses only the lower
triangle for most large symmetric/hermitian matrices.

Regards

Ben


On 30/11/17 16:46, Sharma SRK Chaitanya Yamijala wrote:
> Dear DFTB+ developers,
>
> I am using the output of "makeDensityMatrix" subroutine from a nonSCC
> calculation (on Benzene) for testing our lab code on PLDM. 
>
> As  
>
> \rho_{\mu \nu} = \sum_{i}^{Occ} n_{i} c_{\mu i}c_{\nu i} \\
>
> and
>
> \langle \Phi_{i}| \Phi_{i}\rangle = \sum_{\mu \nu}^{nAOs} c_{\mu
> i}c_{\nu i} S_{\mu \nu} = 1 ~ \forall ~ i\\
>
> I was expecting that sum over (rho(mu,nu) * S(mu,nu)) will give me the
> summation over the fillings of all occupied orbitals (as given by the
> below equation).
>
> \sum_{\mu \nu}^{nAOs} \rho_{\mu \nu} S_{\mu \nu} = \sum_{\mu \nu}
> \sum_{i}^{Occ} n_{i} c_{\mu i}c_{\nu i} S_{\mu \nu} = \sum_{i}^{Occ}
> n_{i} \left(\sum_{\mu \nu} c_{\mu i}c_{\nu i} S_{\mu \nu} \right) =
> \sum_{i}^{Occ} n_{i} 
>
> If the above equation is right, then for the case of benzene and for
> the nonSCC calculation this should give me 30 as the answer (15
> occupied levels and with an occupation number of 2 for each). With the
> minimum modifications to the DFTB+ code, I was not able to get this
> answer. 
>
> *The minimal modifications I did were below:*
> *
> *
> Before the scc loop, I saved the overlap matrix and I have used this
> and the output of "makeDensityMatrix" routine
>
>     if (tCheck) then
>       call unpackHS(overlapReal, over, neighborList%iNeighbor, nNeighbor,&
>         & iAtomStart, iPair, img2CentCell)
>       call blockSymmetrizeHS(overlapReal, iAtomStart)
>       currentOverlap = overlapReal
>     end if
>
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>     !! SCC-loop
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
> ....
> ....
>
> if (tDensON2) then
>               call makeDensityMatrix(SSqrReal, HSqrReal(:,:,iSpin2),
> filling(:,1,iSpin),&
>                   & neighborlist%iNeighbor, nNeighbor, orb,
> iAtomStart, img2CentCell)
>             else
>               call makeDensityMatrix(SSqrReal, HSqrReal(:,:,iSpin2),
> filling(:,1,iSpin))
>
> !********************************************************************
>               sumFilling=0.0d0
>               do iSurf=1,sqrHamSize
>                
>  sumFilling=sumFilling+SSqrReal(iSurf,iSurf)*currentOverlap(iSurf,iSurf)
>               end do
>               do iSurf=1,sqrHamSize-1
>                 do jSurf=iSurf+1,sqrHamSize
>                  
>  sumFilling=sumFilling+2.0d0*SSqrReal(iSurf,jSurf)*currentOverlap(iSurf,jSurf)
>                 end do
>               end do
>               write(*,*)"sumFilling",sumFilling
> !********************************************************************
>
>             end if
>
>
> I believe I am doing something wrong (either in the code or in the
> equation) and any advice on your end is highly appreciated.
>
> Thanking you,
> Sincerely,
> Sharma.
>
> P.S.: You can use https://www.codecogs.com/latex/eqneditor.php to
> visualize the above equations (by copying and pasting them)
>
>
> --------------------------------------------------------------------
> Sharma
> http://www.chem.rochester.edu/groups/huo/people/
>
>
>
> _______________________________________________
> DFTB-Plus-User mailing list
> DFTB-Plus-User at mailman.zfn.uni-bremen.de
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user

-- 
      Dr. B. Hourahine, SUPA, Department of Physics,
    University of Strathclyde, John Anderson Building,
            107 Rottenrow, Glasgow G4 0NG, UK.
    +44 141 548 2325, benjamin.hourahine at strath.ac.uk

2013/4 THE Awards Entrepreneurial University of the Year
      2012/13 THE Awards UK University of the Year

   The University of Strathclyde is a charitable body,
        registered in Scotland, number SC015263

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/attachments/20171130/01d80302/attachment.htm>