[WIEN] DOS question

Peter Blaha pblaha at zeus.theochem.tuwien.ac.at
Wed Nov 5 17:23:06 CET 2003


> I have seen similar things, but forgot to put them to the mailing  list or to investigate them further.  I saw discrepancies between the number of electrons inside the MT (as reported in case.scf2) and the integral of the DOS for the same atom.
> One point may be that the charges in the MT are (I think) derived from the LAPW-representation in A,B and C coefficients, while the DOS is definitely calculated in APW-representation (using 'D' - coefficients).  The change of representation is not 'exact'.

This is NOT true. The partial charges contain the sum of A,B,C coefficients.
The DOS is "exact" and the analytically integrated DOS
(as listed in case.outputt) must give identical numbers to case.scf
(besides of rounding errors, in particular in k-parallel calculations, where
case.scf2 is a sum of many "truncated" numbers)


> f : 0.0282
> total : 12.999 (sum of the above values actually yields 12.993 ; probably a small rounding effect)
> * integrating the local density of states up to the fermi level on a very fine mesh
> s : 2.0031
> p : 6.0835
> d : 4.77 à 4.78 (strong contribution at the fermi level)
> f : 0.958
> total : 12.90 (sum of the above values actually yields 13.819)

There is something wrong. Also the f-charge has to be correct and of course
the total number of electrons must be conserved.

part of case.scf(2):

:FER  : F E R M I - ENERGY(TETRAH.M.)=   0.74554
:CHA001: TOTAL CHARGE INSIDE SPHERE   1 =     1.822375
:PCS001: PARTIAL CHARGES SPHERE =  1 S,P,D,F,      D-EG,D-T2G
:QTL001: 0.1058 0.2144 1.4841 0.0153 0.0000 0.0000 0.0000 0.8429 0.6413 0.0000 0.0000 0.0000


part from case.outputt
# ENERGY      0 total            1 s                1 f
...
  0.74400     2.21   7.9965     0.00   0.1058     0.01   0.0153
  0.74600     2.30   8.0011     0.00   0.1058     0.01   0.0153
                     ^^^^^             ^^^^^             ^^^^^
Between 0.744 and 0.746 the total number of electrons reaches 8 and the
integrated s and f charges agree with case.scf2

Happy debugging.

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