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Dear Vaspians,

I am from chemistry background, so sometimes
I'd like to check the orbital occupation of my system,
(e.g. For 1st atom, there are 2 electrons in p, 4 electrons in d, etc.)
and check the electron counting which you see any inorganic chemistry textbook.

In OUTCAR, total charge table seems to give relevant information.
But I am not sure what to do.

In my OUTCAR,

total charge

# of ion s p d tot
----------------------------------------
1 0.543 0.530 3.025 4.098
2 0.618 1.057 3.640 5.314
...
------------------------------------------------
tot 5.529 10.230 10.304 26.064

What should I do to deduce the orbital occupation information?

Could I interpret the table in the following way? :
"For the 1st atom, there are 0.543 electrons in s, 0.530 electrons in p, and 3.025 electrons in d orbial. The 1st atom have 4.098 valence electrons in total."

Or do I need another values somewhere in OUTCAR or in other files?

Actually, I am not sure about the unit of the charge in the table.
If the above interpretation of mine is right,
could I assign formal charge on each atom as the difference
between the number of occupied electrons in the system
and that in neutral atom?

I used tetrahedrom method, and did not give meaningful RWIGS values.

Happy new year,
and many thanks in advance. (- -) (_ _)


<span class='smallblacktext'>[ Edited ]</span>

A) please note that in all mixed- or plane wave basis set calculations, local quantities (like local charges, local magnetic moments) are obtained by integrating the charge density (or spin density) in the volume of a sphere centered at the respective ions' positions (with radius r=RWIGS)
therefore these numbers are not rigorously defined in the sense that
1) by changing the volume of the sphere (RWIGS), the local charges change as well (it makes no sense to give 'absolute charges', charge transfer effects can however be accounted for)
2) if some spheres overlap, contributions of the overlapping regions are counted twice
3) all charge in the interstitial (space between the spheres) is not summed up in this table (of course it IS included in tht total charge of the cell)

B) the units of the charge in the table are electrons, and you are right with your interpretation (0.543 s-e- for atom 1,... )

C) in principle, some qualitative (or even semi-quantitative) information about formal charges can be given (e.g. delta plus/minus with respect to the free atom) if RWIGS is kept constant for both runs.

D) the integration method does not influence the decomposition into local charges. RWIGS need not be given explicitely if PAW-PPs are used (and LORBIT>=10), because in that case RWIGS as defined for each atom type as in the POTCAR file which is used. IF you want to give RWIGS explicitely (in INCAR), please choose LORBIT=1 or 2.