The ABINIT Users Mailing List ( CLOSED )

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

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