[Wien] Possible bugs in Mixer
Guoping Zhang
gpzhang.physics at gmail.com
Fri Dec 19 20:38:05 CET 2025
Dear Prof. Blaha,
Thank you so much for your insights!
Here is what I did.
I set the charge convergence at 0.0000001, with 50 iterations, I have for
machine 1
has
:DIS : CHARGE DISTANCE ( 0.0000000 for atom 2 spin 1)
0.0000000
-------------------------------------------
machine 2
:DIS : CHARGE DISTANCE ( 0.0000000 for atom 1 spin 1)
0.0000001
Eigenenergies are
57 0.555640059910 0.55363321799308D-03
58 0.555640061603 0.55363321799308D-03
59 0.740271026751 0.00000000000000D+00
60 0.740271028515 0.00000000000000D+00
61 0.748205005635 0.00000000000000D+00
62 0.748205006555 0.00000000000000D+00
-------------------------------------------------------------------
57 0.555640058339 0.55363321799308D-03
58 0.555640061273 0.55363321799308D-03
59 0.740271025639 0.00000000000000D+00
60 0.740271027711 0.00000000000000D+00
61 0.748205004954 0.00000000000000D+00
62 0.748205005071 0.00000000000000D+00
Should I do an energy convergence as well?
Thanks a lot!
Guoping
On Fri, Dec 19, 2025 at 1:54 PM Peter Blaha <peter.blaha at tuwien.ac.at>
wrote:
> Convergence could be the reason that eigenvalues differ by 10**-6 Ry and
> of course also the eigenvectors ....
>
>
> Am 19.12.2025 um 19:48 schrieb Laurence Marks:
> > Sorry Peter, this is not working on the DFT eigenvectors and convergence
> > is not relevant. It is doing a SVD of {YY+lamdba*SY}} to generate a
> > Penrose-Moore pseudoinverse. The vectors of an SVD are not unique within
> > a phase term.
> >
> > On Fri, Dec 19, 2025 at 12:41 PM Peter Blaha <peter.blaha at tuwien.ac.at
> > <mailto:peter.blaha at tuwien.ac.at>> wrote:
> >
> > "different results":
> > I'd expect it is either not fully self-consistent for the
> > quantity/accuracy of interest (do on both computers 100 more
> > iterations), or different hardware (AVXxx, different cpu, cache,
> ...),
> > software like mkl-, ifort- versions or compiler options or ...
> >
> >
> >
> > Am 19.12.2025 um 17:35 schrieb Guoping Zhang:
> > > Dear Profs. Blaha and Marks and wien users,
> > >
> > > I have a question on how the new Mixer is implemented as it gives
> me
> > > different results on different computers. Different results mean
> > that
> > > the eigenvalues differ by 10^-6 ry, so the wavefunctions are even
> > > worse. I am using wien2k_13 version, but there is no difference
> for
> > > newer versions.
> > >
> > >
> > > In FprojmemR1m.F, call DGESVD gets SVD of Vect, but SVD normally
> > > produces an arbitrary sign for U and VT for the same Vect like
> > > vect 1 1 1.7542057564
> > > vect 1 2 1.7522638412
> > > vect 2 1 1.7441856025
> > > vect 2 2 1.7425017533
> > >
> > > In one case, my U is
> > >
> > >
> > > debug3c.outputm:MMT91 U VT 1 1 -0.7091042206
> > -0.7074733729
> > > debug3c.outputm:MMT91 U VT 1 2 -0.7051036834
> > -0.7067399994
> > > debug3c.outputm:MMT91 U VT 2 1 -0.7051036834
> > -0.7067399994
> > > debug3c.outputm:MMT91 U VT 2 2 0.7091042206
> > 0.7074733729
> > >
> > > Another case has
> > >
> > > debug11.outputm:MMT91 U VT 1 1 0.7091042206
> > 0.7074733728
> > > debug11.outputm:MMT91 U VT 1 2 -0.7051036834
> > 0.7067399994
> > > debug11.outputm:MMT91 U VT 2 1 0.7051036834
> > -0.7067399994
> > > debug11.outputm:MMT91 U VT 2 2 0.7091042206
> > 0.7074733728
> > >
> > > I run 4 iterations to activate the mixer. When I diff case.scf,
> > these two
> > > cases have no difference to the last digit,
> > >
> > > But after the mixing, it differs a lot though the total energy is
> the
> > > same (which is not my interest).
> > >
> > > My questions are (1) whether the new mixer finally uses some
> products
> > > like (U x VT) to generate the new charge density, and (2) whether
> you
> > > have examples that I use to verify this arbitrary sign does not
> > matter.
> > >
> > > Thank you so much in advance!
> > >
> > > Best wishes,
> > >
> > > Guoping
> > >
> > >
> > > _______________________________________________
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> >
> > --
> >
> -----------------------------------------------------------------------
> > Peter Blaha, Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> > Email: peter.blaha at tuwien.ac.at <mailto:peter.blaha at tuwien.ac.at>
> > WWW: http://www.imc.tuwien.ac.at <http://www.imc.tuwien.ac.at>
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> >
> -------------------------------------------------------------------------
> >
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> >
> >
> >
> > --
> > Emeritus Professor Laurence Marks (Laurie)
> > Northwestern University
> > Webpage <http://www.numis.northwestern.edu> and Google Scholar link
> > <http://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en>
> > "Research is to see what everybody else has seen, and to think what
> > nobody else has thought", Albert Szent-Györgyi
> >
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> --
> -----------------------------------------------------------------------
> Peter Blaha, Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Email: peter.blaha at tuwien.ac.at
> WWW: http://www.imc.tuwien.ac.at WIEN2k: http://www.wien2k.at
> -------------------------------------------------------------------------
>
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