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

[Eskil Varenius]

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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