[Pw_forum] Normalization of the atomic wave functions

[Henning Glawe]

On Wed, Jul 18, 2007 at 11:01:20AM +0200, degironc wrote:
> The projection in LDA+U is however defined on the individual atoms (even 
> if technically bloch states are involved) and these
> wfc are normalized.
> hope this helps,

ok, in the pen-and-paper check this seems ok.
The reason for my original question was: In my system (CaCuO2 in an 
2D-AFM sqrt(2)*sqrt(2)*1 unit cell), when using atomic states as the
projectors for the projectors, I am getting a lot of matrix elements of the
occupation matrix significantly larger than 1 (between 4 and 5(!)).

The Hubbard term in the total energy, as I understand from Matteo 
Cococcioni's thesis (and the meaning of the word 'occupation'), seems only 
well-defined as long as these matrix elements are between 0 and 1.

Now I am trying to investigate where these occupation values are coming
from and started by looking at the single scalar products <evc|satwfc> used
in the calculation of the n. Finding out that already these values are too 
big (i.e. larger than 1) in my system, I tried to investigate the 
normalization of the atomic wave functions and checked also the 
known-working example of FeO.

In the FeO example, the occupation matrix elements are also slightly bigger
than 1 (1.002 in feo_standard.out), but I was thinking that this was related
to numerical errors. Now I am asking myself (and the forum ;) ): is there any
part in the formalism and/or code which restricts the occupation to the
right regime i.e. 0..1 ?

-- 
c u
henning