The ABINIT Users Mailing List ( CLOSED )

[Anglade Pierre-Matthieu <anglade@gmail.com>]

Hi Matthieu,

Have you noticed that there is two case depending on your k-point mesh ?
In the wrong case, obtained with meshes like 36 36 1, 12 12 1, 9 9 1,
6 6 1, the potential residual you get is a function of the number of
k-point you use :The less k-point,  the bigger the vres2.
Yet If one uses a single k-point or some other meshes (tried 211, 221,
441, 551, 771, 881, 35 35 1)  everythings converge fine.

If one or a few k-point were getting a  "shift"  because of bad
application of symmetries in the nonsymmop case,  don't you think it
could lead to this behavior ?

Have you already explored this idea ?

Regards

PMA


On Wed, Mar 4, 2009 at 1:40 PM, matthieu verstraete
<matthieu.jean.verstraete@gmail.com> wrote:
> No improvement unfortunately... You really need the symops.
>
> Matthieu
> - Show quoted text -
>
> On Tue, Mar 3, 2009 at 9:21 PM, Anglade Pierre-Matthieu <anglade@gmail.com>
> wrote:
>>
>> What about iprcel 145 ?
>>
>>
>> On Tue, Mar 3, 2009 at 7:17 PM, matthieu verstraete
>> <matthieu.jean.verstraete@gmail.com> wrote:
>> > The graphene is basically metallic, and I am treating it as such, but
>> > this
>> > may indeed be part of the problem (hesitating between metallic and
>> > semiconducting screening). I also tried iprcel 45 (always!) but it
>> > doesn't
>> > help.
>> >
>> > Cheers
>> >
>> > Matthieu
>> >
>> >
>> >
>> > On Tue, Mar 3, 2009 at 6:55 PM, Anglade Pierre-Matthieu
>> > <anglade@gmail.com>
>> > wrote:
>> >>
>> >> Hi Matthieu
>> >>
>> >> Is it possible that, for the run that doesn't converge tolvrs, at one
>> >> or another step, the system gets in a metallic state that makes the
>> >> convergence of potential more difficult ?
>> >>
>> >>
>> >> On Tue, Mar 3, 2009 at 5:20 PM, matthieu verstraete
>> >> <matthieu.jean.verstraete@gmail.com> wrote:
>> >> > Ok, it's better (thanks to PMA), but still not entirely satisfactory:
>> >> > with
>> >> > nline 9, the tolwfr goes down, albeit more slowly, to 1.e-17 (so
>> >> > far).
>> >> > However the tolvrs is still stuck at 1.e-4 after 70 steps.
>> >> >
>> >> > With all the symops I get
>> >> >
>> >> >  ETOT 32  -11.444990018007     1.243E-14 9.972E-21 3.357E-20
>> >> > 0.000E+00
>> >> > 0.000E+00
>> >> >
>> >> > beautiful... So why is it so dependent on the non-symmorphic
>> >> > operations?
>> >> > The
>> >> > number of kpoints is the same.
>> >> >
>> >> > For the symmorphic operations in the normal cell, you no longer have
>> >> > inversion symmetry. Changing to a cell with inversion symmetry
>> >> > (origin
>> >> > in
>> >> > the middle of the C-C bond), many more of the operations are
>> >> > non-symmorphic;
>> >> > neglecting these you do not even have a null force on the atoms (only
>> >> > 8
>> >> > symops left, 343 kpt instead of 127). However, it looks like all the
>> >> > other
>> >> > tolerances are converging:
>> >> >
>> >> >  ETOT 21  -11.444989920147    -8.717E-12 1.188E-13 2.693E-05
>> >> > 8.456E-04
>> >> > 4.227E-04
>> >> >
>> >> > So, it looks like the wfr and potential convergence depends on having
>> >> > inversion symmetry, whereas getting correct forces needs some of the
>> >> > other
>> >> > symops (probably the 3-axes - I am now trying with a cell preserving
>> >> > both
>> >> > inversion and 3-axes).
>> >> >
>> >> > Matthieu
>> >> >
>> >> >
>> >> > On Tue, Mar 3, 2009 at 8:44 AM, Anglade Pierre-Matthieu
>> >> > <anglade@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi Matthieu,
>> >> >>
>> >> >> Could it be related to the default value of nline which is sometime
>> >> >> a
>> >> >> bit too small for large systems ? Have you tried a larger value for
>> >> >> nline in the case with removed symmetry operations ? If so, is the
>> >> >> behavior similar ?
>> >> >>
>> >> >> regards
>> >> >>
>> >> >> PMA
>> >> >>
>> >> >> On Tue, Mar 3, 2009 at 12:29 AM, Matteo Giantomassi
>> >> >> <Matteo.Giantomassi@uclouvain.be> wrote:
>> >> >> >  Hello abinists,
>> >> >> >>
>> >> >> >> I have come upon a strange behavior in abinit (not the first, of
>> >> >> >> course)
>> >> >> >> and
>> >> >> >> was wondering if anyone had heard of it or an explanation (v5.6
>> >> >> >> on
>> >> >> >> opteron
>> >> >> >> 64 bit RHEL, g95 compiled, sequential).
>> >> >> >>
>> >> >> >> In converging a ground state for graphene (what else), I need to
>> >> >> >> use
>> >> >> >> only
>> >> >> >> symmorphic symmetry operations. The strange behavior is that,
>> >> >> >> without
>> >> >> >> the
>> >> >> >> non-symmorphic symmetry operations, abinit does not converge the
>> >> >> >> wavefunctions below 1.e-13 or so (even after 200 steps), and the
>> >> >> >> eigenvalues
>> >> >> >> are not converged below mHa accuracy. With all the symops the
>> >> >> >> convergence
>> >> >> >> down to tolwfr 1.e-20 is effortless. Why the difference?
>> >> >> >> Numerical
>> >> >> >> noise
>> >> >> >> is
>> >> >> >> one possibility, but plenty of symops are left in the
>> >> >> >> calculation...
>> >> >> >>
>> >> >> >  Hi, Matthieu
>> >> >> >
>> >> >> >  I've never encountered such a kind of problem but
>> >> >> >  it might be related to a partial fulfillment of the symmetry
>> >> >> > properties
>> >> >> >  of the density and of the generated potentials.
>> >> >> >  Do you have the same number of k-points in the IBZ when
>> >> >> > non-symmorphic
>> >> >> >  operations are removed?
>> >> >> >
>> >> >> >  Just for curiosity: are you pruning non-symmorphic ops because
>> >> >> > you
>> >> >> > want
>> >> >> > to
>> >> >> >  generate a KSS file for GW calculations with abinit?
>> >> >> >  In this case please note that symmorphi=0 is not mandatory
>> >> >> > anymore
>> >> >> >  as the GW part is now able to handle non-symmorphic space groups.
>> >> >> >
>> >> >> >  Cheers,
>> >> >> >  Matteo
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> Pierre-Matthieu Anglade
>> >> >>
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >> > Dr. Matthieu Verstraete
>> >> >
>> >> > European Theoretical Spectroscopy Facility (ETSF)
>> >> > Dpto. Fisica de Materiales,
>> >> > U. del Pais Vasco,
>> >> > Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
>> >> > E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390
>> >> >
>> >> > Mail : matthieu.jean.verstraete@gmail.com
>> >> > http://www-users.york.ac.uk/~mjv500
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Pierre-Matthieu Anglade
>> >>
>> >
>> >
>> >
>> > --
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > Dr. Matthieu Verstraete
>> >
>> > European Theoretical Spectroscopy Facility (ETSF)
>> > Dpto. Fisica de Materiales,
>> > U. del Pais Vasco,
>> > Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
>> > E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390
>> >
>> > Mail : matthieu.jean.verstraete@gmail.com
>> > http://www-users.york.ac.uk/~mjv500
>> >
>>
>>
>>
>> --
>> Pierre-Matthieu Anglade
>>
>
>
>
> --
> - Show quoted text -
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr. Matthieu Verstraete
>
> European Theoretical Spectroscopy Facility (ETSF)
> Dpto. Fisica de Materiales,
> U. del Pais Vasco,
> Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
> E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390
>
> Mail : matthieu.jean.verstraete@gmail.com
> http://www-users.york.ac.uk/~mjv500
>



-- 
Pierre-Matthieu Anglade