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

[Jens Jørgen Mortensen]

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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>> gpaw-users at listserv.fysik.dtu.dk
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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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