[Wien] spin configuration for charge state
Laurence Marks
L-marks at northwestern.edu
Tue May 10 14:40:39 CEST 2016
To clarify one point, you have to be careful about the meaning of Co"4+".
The "4+" is a formal valence, which is quite well reproduced by the
bond-valence sums (BVS), e.g. do "x nn ; grep Bond *tnn". It is also what
people use when they refer to different atom states as observed by XPS,
EELS etc.
This is different from the actual charge within the muffin tins (look at
the relevant :CTO), the d-electron density from the density matrix, the
spin from the magnetic moment, the Bader charge and the dynamic
polarization charge (Born charge).
On Tue, May 10, 2016 at 7:33 AM, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:
> 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
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
> WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php
> --------------------------------------------------------------------------
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--
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A
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