[gpaw-users] GPAW dev r7883: Spin-pol vdW-DF2 diverges

Tue Apr 26 07:15:54 CEST 2011

Hi again,
Thanks a lot Duy and Jess!
Using Jess proposed Mixer settings actually works in my real calculations as
well as the atomization script. Apparently I didn't try that mixer setting
myself. I will try more values before asking next time if I ever run into
similar problems again.

Thanks again for your kind help, consider the problem solved!

Cheers,
Eskil

2011/4/25 Jess Wellendorff <jesswellendorff at gmail.com>

>  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>
>
>> 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> 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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>> > gpaw-users at listserv.fysik.dtu.dk
>> > https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
>> >
>>
>
>
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