[Wien] How to find the valency of an element from case.scf file?

[Laurence Marks]

No, the valency of Yb is not 2.28 and B is not 1.37

Chemical "Valence" stems back to the original work of Pauling, and in a
modern interpretation is very close to the Bond Valence Sum which are given
by "x nn". It depends upon local co-ordination.

Experimental "valence" measurements such as EELS, XPS have been
cross-correlated against the chemical valence.

Plane wave or (L)APW DFT calculations do not give this, except in the bond
distances if they are minimized and sometimes in the band occupancies. Pure
orbital approaches do.

A different approach is the Bader charge, which connects to the ionicity
and sometimes the valence.

The charge within the RMT is related to the valence, but is not the same
and is rarely that useful.

(And one has Born effective charges, and others...)

On Sun, Mar 24, 2019 at 1:05 PM Anup Shakya <npshakya31 at gmail.com> wrote:

> Dear All,
>
> I have done non-magnetic calculations for YbB6 where Yb exist in mixed
> valent state. The  scf has been converged using U and J along with SOC. I
> wanted to get the information about the valency of the respective atoms
> after convergence and when I checked the case.scf file I found the
> following information.
>
> CHARGES OF MIXED CHARGE DENSITY
> :CTO   : INTERSTITIAL     UP =     5.246046 DN =     5.246046 TOT =
> 10.492091
> :CTO001: CHARGE SPHERE  1 UP =    33.860076 DN =    33.860076 TOT =
> 67.720153
> :CTO002: CHARGE SPHERE  2 UP =     1.815644 DN =     1.815644 TOT =
>  3.631288
> :CTO003: CHARGE SPHERE  3 UP =     1.815651 DN =     1.815651 TOT =
>  3.631301
>
> SPIN MAGNETIC MOMENTS OF MIXED CHARGE DENSITY
> :MMINT:  MAGNETIC MOMENT IN INTERSTITIAL  =    0.00000
> :MMI001: MAGNETIC MOMENT IN SPHERE   1    =    0.00000
> :MMI002: MAGNETIC MOMENT IN SPHERE   2    =    0.00000
> :MMI003: MAGNETIC MOMENT IN SPHERE   3    =    0.00000
> :MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =    0.00000
>
> It can be seen clearly that the 1st atom total charge is given as 67.72
> which is close to Yb atom i.e, 70. So, if I subtract 70 from the above
> number I get around 2.28. Similarly the 2nd and third atoms are B where
> after subtracting the valency of B I get a value of around 1.37. Does this
> mean that the ground state valency of Yb is 2.28 and B is 1.37 from the
> calculations? Please suggest. Looking forward to hearing from you.
>
> Sincerely,
> Anup Pradhan Sakhya,
> Visiting Fellow,
> TIFR
>
>

-- 
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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