[ase-users] magnetic moments

[Vivien Petzold]

Dear ASE users,

I have made some mysterious observations by doing the following:

 > from gpaw import restart
 > atoms, calc = restart(<myfile>)

<myfile> is a gpw-file containing an originally spin-polarized 
calculation of a Cl2 molecule. Both atoms had magmom=1 in the 
calculation that generated myfile.

 > atoms.get_magnetic_moments()
array([ 0.,  0.])
 > atoms[0]
Atom('Cl', [6.0, 6.5, 8.007541], tag=0, magmom=0.0, index=0)
 > atoms[1]
Atom('Cl', [6.0, 6.5, 5.992459], tag=0, magmom=0.0, index=1)

The information of the initial magmoms is apparently lost. So, I am 
setting them again:

 > atoms.set_magnetic_moments((1,1))
 > atoms.get_magnetic_moments()
array([ 0.,  0.])

Hmmm ...? But, interestingly

 > atoms[0]
Atom('Cl', [6.0, 6.5, 8.007541], tag=0, magmom=1.0, index=0)
 > atoms[1]
Atom('Cl', [6.0, 6.5, 5.992459], tag=0, magmom=1.0, index=1)

What is going on? Are the magnetic moments set or not? And why are they 
not stored in the gpw-file (a question that should rather go to the gpaw 
mailing list)?

Thanks for any help,
Vivien