[gpaw-users] Ti atom GS convergence problem and wrong Magnetic moment

[Jakob Blomquist]

Another thing.
For the same titanium atom in a box if I set hund=True and occupation = 
FermiDirac(width=0.0, fixmagmom=True)
I will get a text output like below: How come I get +2 in Magnetic 
Moment for Ti using Hund's rule?


*****************
            Time      WFS    Density  Energy       Fermi  Poisson  MagMom
iter:   1  15:15:06  +2.6              -317.47976   0      14       +2.0000
iter:   2  15:15:07  +0.8              -360.61764   0                 
+2.0000
iter:   3  15:15:08  -0.3               -362.63939   0                  
+2.0000
iter:   4  15:15:16  +0.8   -0.1     -263.03619   0      10       +2.0000
iter:   5  15:15:25  +1.1   -0.1     -14.93935     0      13       +2.0000
iter:   6  15:15:33  +0.7   -0.6      6.01038       0      10       +2.0000
iter:   7  15:15:40  +0.4   -0.8      0.46328       0       6        +2.0000

*****************

Dr Jakob Blomquist
Associate Professor
Dep. of Material Science
IMP, School of Technology
Malmo University
SWEDEN
+46(0)40 6657751
jakob.blomqvist at mah.se


On 10/17/2011 11:43 AM, Jakob Blomquist wrote:
> I'm having a surprisingly hard time with a simple Ti-atom.
> The magnetic moment doesn't follow Hund's rule (should be a 3F2 state)
> but end up with +4 if it converges at all.
> It doesn't matter much if I run with PBC = True or not or if the box is
> symmetric or not.
>
> Is this something known?
>
> scrip run e.g:
>
> *****************
> from ase import Atoms, Atom
> from gpaw import GPAW, FermiDirac, MixerSum
> from ase.parallel import parprint
>
> Ti = Atoms('Ti')
>
> Ti.center(vacuum=6.)
> #Ti.cell[1,1] += 1.0
> #Ti.cell[2,2] += (-1.0)
>
> #mixer = MixerSum(beta=0.1, nmaxold=3, weight=1.0)
> name = 'Ti'
> calc = GPAW(txt=name+'.txt',
>               basis='dz(dzp)',
>               nbands=-4,
>               h = 0.16,
>               xc='PBE',
>               hund=True,
>               )
>
> Ti.set_calculator(calc)
> e = Ti.get_potential_energy()
>
> *****************
>
> ASE rev. 3.5.0.2113
> GPAW rev. 0.8.0.8008
>