[gpaw-users] Ni in a box doesn't convergence and spin-polarized set-up

[Alvaro Vazquez-Mayagoitia]

Hi,

I could to converge the isolated atom with the correct spin using a  bigger
cell (12,11,10) .

Now my problem is with the dimer and trimer which should have unpaired
electrons in the ground state.

Thanks
Alvaro
On Dec 13, 2011 11:32 AM, "Nichols A. Romero" <naromero at alcf.anl.gov> wrote:

> I think we tried at 0.10 and it didn't work.
>
> Alvaro,
>
> Can you play around with this script and see if you can get it to converge?
>
> Nichols A. Romero, Ph.D.
> Argonne Leadership Computing Facility
> Argonne National Laboratory
> Building 240 Room 2-127
> 9700 South Cass Avenue
> Argonne, IL 60490
> (630) 252-3441
>
>
> ----- Original Message -----
> From: "Ask Hjorth Larsen" <askhl at fysik.dtu.dk>
> To: "Alvaro Vazquez Mayagoitia" <fray.gory at gmail.com>
> Cc: "Nichols A. Romero" <naromero at alcf.anl.gov>, "gpaw-users" <
> gpaw-users at listserv.fysik.dtu.dk>
> Sent: Tuesday, December 13, 2011 6:53:01 AM
> Subject: Re: [gpaw-users] Ni in a box doesn't convergence and
> spin-polarized set-up
>
> Hi
>
> On Tue, 13 Dec 2011, Alvaro Vazquez Mayagoitia wrote:
>
> > Hi Ask,
> >
> > yes, Ni is a weird/tricky example, even for gaussian basis set codes
> >
> > I tried adding
> >  fixmom=True
> > and
> >  occupations=FermiDirac(x)
> > (with 0<x<1)
> >
> > and no success,
> >
> > Could you provide me an example, please?
> >
> >
> > Thank you in advance,
> > -Alvaro
>
> Note that it isn't entirely trivial whether the calculation makes *sense*
> when the occupations are fractional - but I think it's the most correct
> way (given multiple "incorrect" alternatives) to deal with the problem.
>
> This works:
>
> from ase import Atoms
> from gpaw import GPAW, FermiDirac, PoissonSolver
>
> system = Atoms('Ni')
> system.center(vacuum=5.0)
> calc = GPAW(occupations=FermiDirac(0.3), hund=True,
>             poissonsolver=PoissonSolver(relax='GS', eps=1e-8))
>
> system.set_calculator(calc)
> system.get_potential_energy()
>
>
>
> (the Poisson solver just makes it take less time)
>
> You can probably reduce the Fermi smearing (just tested that it works down
> to 0.1).
>
> Regards
> Ask
>
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