[gpaw-users] Problems with converging a molecule in a high spin state

[Keld Lundgaard]

Dear GPAW-users


I am having problems with converging high state system, so I would like to
hear if this is something other people have found solutions to or that it
is not something that GPAW is capable of.

Best regards

Keld Lundgaard
PhD Student at CAMD, DTU, visitor at SUNCAT, SLAC


*Below the problem is illustrated:*

To illustrates how it will not converge:
iter:  39  16:06:22  -1.3   -2.2       -1.911203  0      4        +3.0000
iter:  40  16:06:25  -0.8   -1.9       -1.839254  0      4        +3.0000
iter:  41  16:06:28  -0.3   -1.6       -1.520076  0      5        +3.0000
iter:  42  16:06:31  +0.3   -1.5       -0.797068  0      5        +3.0000
iter:  43  16:06:35  +0.3   -1.4       -0.021212  0      5        +3.0000
iter:  44  16:06:38  +0.1   -1.4        0.478514  0      5        +3.0000
iter:  45  16:06:41  +0.1   -1.4        0.848129  0      6        +3.0000
iter:  46  16:06:44  -0.2   -1.4        0.907136  0      7        +3.0000
iter:  47  16:06:47  +0.1   -1.3        1.309572  0      7        +3.0000
iter:  48  16:06:51  -0.1   -1.4        0.984924  0      7        +3.0000
iter:  49  16:06:54  -0.3   -1.4        0.291408  0      8        +3.0000
iter:  50  16:06:58  +0.5   -1.5       -1.285408  0      8        +3.0000
iter:  51  16:07:01  +0.0   -1.7       -1.476658  0      7        +3.0000
iter:  52  16:07:04  +0.3   -1.4       -0.754970  0      7        +3.0000
iter:  53  16:07:07  +0.0   -1.5       -0.415069  0      5        +3.0000
iter:  54  16:07:10  -0.3   -1.5       -0.261194  0      6        +3.0000
iter:  55  16:07:14  -0.1   -1.5        0.201020  0      6        +3.0000
iter:  56  16:07:17  +0.2   -1.4       -0.816876  0      8        +3.0000
iter:  57  16:07:20  -0.4   -1.8       -1.396651  0      6        +3.0000


*Script*
from ase import Atoms
from gpaw.cluster import Cluster
from gpaw import GPAW, FermiDirac, MixerSum

h =.2
functional = 'PBE' #'PBE'  #
Hubmode = 'noHubU'#'U0_3d'
molecule_name = 'ScH'#'ScH'
tot_mag = 3
spinpol=1

data_mol={'symbols':molecule_name,
         'positions':     ([
                           [ 0.,  0.,  0.],
                           [ 0.,  0.,  1.775],
                           ]),
          'magmoms':[0.,0.]
          }

s = Cluster(Atoms(
              data_mol['symbols'],
              positions=data_mol['positions'],
              magmoms=data_mol['magmoms'])
        )
s.set_initial_magnetic_moments([tot_mag,0])
s.minimal_box(4.,h=h)

c = GPAW(h=h,
         kpts = (1,1,1),
         occupations=FermiDirac(
                                width=0.0,
                                fixmagmom=True
                                ),
         convergence = {'energy': 1.0e-3,  # eV / electron
            'density': 5.0e-4,
            'eigenstates': 1.0e-5,  # eV^2 / electron
            'bands': 'occupied'
            },
         stencils=(4, 3),
         mixer = MixerSum(0.1,5,100),
         nbands = -40,
         spinpol=spinpol,
         maxiter = 1000,
         xc = functional,
         )

s.set_calculator(c)
s.get_potential_energy()
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