[Wien] spin configuration for charge state

[Peter Blaha]

a) I don't think that you will ever get a 3d-occupation which is in 
agreement with the "formal" valence (therfore this is called "formal").
This starts even for a very ionic TiO2, where formally the 3d electrons 
of Ti4+ should all be empty, but are not in reality.

b) Try to stabilize a "high-spin" state for Co by changing the 0.8 on 
spin-dn to 0.2, and the 0.59 to 0.9 in spin-up.
After modification of the dmatup/dn files, run:

x orb -up/dn
runsp -orbc
save constraint_high_spin
runsp -orb

and check the final results, if the spin (charge) state has changed.
Also compare the total energies of the present and the new solution.


On 05/10/2016 01:54 PM, Komal Bapna wrote:
> Dear Prof. Peter
> Thank you for your kind reply..
>
> The Density matrix for Co up spin is..
>           0.84607  0.00000  0.00000  0.00000 -0.08661
>           0.00000  0.92206  0.00000  0.00000  0.00000
>           0.00000  0.00000  0.59673  0.00000  0.00000
>           0.00000  0.00000  0.00000  0.92206  0.00000
>          -0.08661  0.00000  0.00000  0.00000  0.84607
> Total electrons: 4.13298
> and Density matrix for Co dn spin is:
>           0.20583  0.00000  0.00000  0.00000  0.06263
>           0.00000  0.80064  0.00000  0.00000  0.00000
>           0.00000  0.00000  0.25923  0.00000  0.00000
>           0.00000  0.00000  0.00000  0.80064  0.00000
>           0.06263  0.00000  0.00000  0.00000  0.20583
> Total electrons: 2.27217
>
> This gives me the net spin moment of 1.86 muB on Co.
> I understood by changing the occupancies we can change the spin state.
> Still I am confused whether I can use these occupation numbers of
> electrons in the respective orbitals to find the spin state of Co.Here,
> total number of electrons is 6.4, 1.4 electrons higher than the expected
> value for Co4+ ion. I may consider the extra electrons due to the
> bonding of Co-O bonds. But, I am really unable to calculate the spin
> state from the present configuration. Please suggest how to calculate
> spin state for the given configuration, so that I can modify further.
>
> Thanks and Regards
>
> On Mon, May 9, 2016 at 3:59 PM, Komal Bapna <komal.bapna at gmail.com
> <mailto:komal.bapna at gmail.com>> wrote:
>
>     Sir,
>
>     Its true that we can not generate "ionic" electron density with lstart/dstart. When I tried to modify .inst file according to the Co4+ ionic state, it showed error.
>
>     My query is that how can we generate spin state configuration for such an ionic state, it spin states for Co and Co4+ are different and accordingly the magnetic moments.
>
>
>     Please suggest.
>
>
>     Thanks
>
>
>     On Fri, May 6, 2016 at 3:18 PM, Komal Bapna <komal.bapna at gmail.com
>     <mailto:komal.bapna at gmail.com>> wrote:
>
>         Dear Wien users
>
>         I am working on Sr2CoO4. Here I wanted to study the system with different spin state configuration of Co4+, which is known to be valence state of Co in this system. I could understand how to create:
>             (a) High-spin configuration
>             (b) Intermediate spin configuration
>             (c) Low-spin configuration
>         for the given Co atoms in the .inst file as
>
>         Co
>         Ar 3
>         3, 2,2.0  N
>         3, 2,2.0  N
>         3,-3,3.0  N
>         3,-3,0.0  N
>         4,-1,1.0  N
>         4,-1,1.0  N   (for HS state)
>         and
>         Co
>         Ar 3
>         3, 2,2.0  N
>         3, 2,2.0  N
>         3,-3,2.0  N
>         3,-3,1.0  N
>         4,-1,1.0  N
>         4,-1,1.0  N  (for IS state)
>
>
>         But my query is that .inst file takes Co as neutral atom (9
>         electrons:3d74s2) and accordingly its spin state. As if Co were in 4+ state, I would have 5 electrons in 3d state (3d54s0) rather 9 electrons as is revealed from .inst file now.
>
>         Please suggest me how to give spin state for Co4+ for this system.
>
>
>         Thanks
>
>
>
>         --
>         *Komal*
>
>
>
>
>     --
>     *Komal*
>
>
>
>
> --
> *Komal*
>
>
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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