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

[Keld Lundgaard]

Thank you Marcin.

@ JJ
Yes, it is correct that the tot_mag should be 2 and not 3 for the high spin
state.

- Keld

On Mon, Jan 21, 2013 at 12:13 AM, Jens Jørgen Mortensen
<jensj at fysik.dtu.dk>wrote:

>  Den 20-01-2013 21:18, Marcin Dulak skrev:
>
> Hi,
>
> On 01/17/13 01:11, Keld Lundgaard wrote:
>
> 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.
>
> such systems will be tricky in probably any DFT program.
> I managed to converge it with the new Sc setup, still not with the old one.
> I got 2.4 eV for dissociation energy of singlet and 0.7 of triplet. The
> triplet has half occupied homo.
> The dissociation energy for the triplet one is far from the article you
> are probably trying to reproduce:
> doi:10.1063/1.3489110
>             distance | dissociation energy
> singlet 1.760 2.59 eV
> triplet 1.844 2.33
>
> doi:10.1063/1.2162161
> singlet 60.5 * kcal / mol = 2.62
>
> I would recommend to verify the triplet result with NWchem.
> Check also if doi:10.1063/1.3489110 provides any further details
> about the electronic state of triplet ScH they got.
>
>
> Shouldn't tot_mag be 2 instead of 3?
>
> Jens Jørgen
>
>
>  Best regards,
>
> Marcin
>
>
>  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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>
>
>
> --
> ***********************************
>
> Marcin Dulak
> Technical University of Denmark
> Department of Physics
> Building 307, Room 229
> DK-2800 Kongens Lyngby
> Denmark
> Tel.: (+45) 4525 3157
> Fax.: (+45) 4593 2399
> email: Marcin.Dulak at fysik.dtu.dk
>
> ***********************************
>
>
>
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>
>
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