[gpaw-users] GPAW dev r7883: Spin-pol vdW-DF2 diverges
Jess Wellendorff
jesswellendorff at gmail.com
Mon Apr 25 21:20:50 CEST 2011
Hi Eskil,
I think you will find that your issue is largely cured by using a
somewhat less aggressive density mixing for the hydrogen atom, than the
GPAW default, e.g.
********
from gpaw import GPAW, Mixer
calc = GPAW(....., mixer=Mixer(0.1, 5), ........)
********
with which I found the H atom in the example to converge nicely in less
than 20 iterations with a=8 and xc='vdW-DF-2'.
The default mixer handles the spinpaired H2 molecule well, but is
sometimes a bit too aggressive for isolated atoms in vacuum, especially
if these have several unpaired "magmoms" in their ground state.
Cheers,
Jess Wellendorff
Den 25-04-2011 16:35, Eskil Varenius skrev:
> Thanks for the idea!
> Yes, I've tried changing eigensolver to 'cg' and played a little with
> the mixer settings, but with no improvement. Trouble is, in other
> calculations I've sometimes encountered convergence errors which can
> be solved by following instructions on the convergence page. But those
> times the energy is always close to some value, it just won't converge
> the last decimals. Or the log10 error refuses to go below -3. In this
> case the whole calculation rapidly blows out of proportion. Energy
> jumps of several hundred eV for a single hydrogen atom seems really
> weird. And the log errors are often positive between iterations.
>
> Have anyone successfully did a spin-polarised vdW-DF2 calculation? If
> so, on what system? I would gladly try it here. Also, if one has a
> working setup for spin-polarised vdW-DF2 it would be interesting to
> see if the hydrogen atomization example works in that setup.
>
> Best regards,
> Eskil
>
>
> 2011/4/25 Duy Le <ttduyle at gmail.com <mailto:ttduyle at gmail.com>>
>
> The convergence issues are discussed in:
> https://wiki.fysik.dtu.dk/gpaw/documentation/convergence/convergence.html#convergence
> Have you ever tried them? Especially to change the eigensolver and
> the mixing
> --------------------------------------------------
> Duy Le
> PhD Student
> Department of Physics
> University of Central Florida.
>
> "Men don't need hand to do things"
>
>
>
> On Mon, Apr 25, 2011 at 9:32 AM, Eskil Varenius
> <eskil.varenius at gmail.com <mailto:eskil.varenius at gmail.com>> wrote:
> > Dear GPAW users and developers,
> > Background
> > I'm a master student at Chalmers, Gothenburg, Sweden. In my
> thesis work I
> > want to use GPAW to calculate total energies with the vdW-DF
> functional. I
> > also want to use the recent second version, the vdW-DF2. Since
> the second
> > version is not easily accessible in the current release version
> of GPAW
> > (r6974) I asked our cluster admins if they could install the lastest
> > dev-version of GPAW (r7883 at time of asking). In this version
> the vdW-DF2
> > is easily accessible. However I encountered a major problem.
> Since this is a
> > dev checkout I want to ask if this problem has been fixed in later
> > dev-versions and if I should ask the cluster admin to upgrade.
> > Problem
> > Spin-polarized calculations with vdW-DF2 doesn't work. It more
> or less
> > diverges after a few iterations.
> > However, spin-paired calculations with vdW-DF2 seems to work.
> > Spin-paired / polarized calculations with vdW-DF (version 1)
> seems to work
> > fine.
> > Steps to reproduce
> > 1. Install GPAW dev-version 7883.
> > 2. Run example script for hydrogen atomization energies
> >
> (https://wiki.fysik.dtu.dk/gpaw/tutorials/atomization/atomization.html)
> with
> > xc='vdW-DF2', and a=8.
> > 3. Check the output. For the first hydrogen calculation I got:
> > Number of Valence Electrons: 1
> > log10-error: Total Iterations:
> > Time WFS Density Energy Fermi Poisson
> MagMom
> > iter: 1 20:54:30 -0.3 -1.31548 0 14
> +1.0000
> > iter: 2 20:54:30 -1.8 -1.35790 0
> +1.0000
> > iter: 3 20:54:30 -2.3 -1.36544 0
> +1.0000
> > iter: 4 20:54:49 -2.7 -1.2 -29.93035 0 6
> -1.0000
> > iter: 5 20:55:09 -0.4 -0.4 -10.44161 0 6
> +1.0000
> > iter: 6 20:55:28 +0.5 -0.2 -26.34328 0 4
> -1.0000
> > iter: 7 20:55:46 +1.0 -0.1 -40.33089 0 6
> +1.0000
> > iter: 8 20:56:02 +0.8 -0.0 -57.44584 0 6
> -1.0000
> > iter: 9 20:56:18 +1.4 -0.0 -56.50579 0 10
> +1.0000
> > iter: 10 20:56:37 +1.1 +0.0 -170.18543 0 14
> -1.0000
> > iter: 11 20:56:54 +1.9 -0.2 -142.87739 0 8
> +1.0000
> > iter: 12 20:57:12 +0.3 -0.5 -116.98545 0 10
> -1.0000
> > I would be very grateful if someone could check this at least
> briefly since
> > my thesis work would benefit a lot from beeing able to do
> spin-polarized
> > vdW-DF2 calculations.
> > Best regards,
> > Eskil Varenius, Chalmers Master Student
> > _______________________________________________
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> > https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
> >
>
>
>
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