[Pw_forum] The 'PAWPROJ' option in projwfc.x

[Holzwarth, Natalie]

Dear Ifeanyi J.,
        The pawproj=.true. option calculates the overlap of each PAW
projector function with the pseudo wavefunction in order to estimate the
charge within the augmentation radius associated with each atom.    If you
have two projector and basis functions for H in the s channel, they would
both contribute.     By summing the two contributions you can approximate
the charge within the augmentation radius.    In principle, if your
projector and basis set "spans" the function space, you would get a good
estimate of the charge.    See attached notes if interested in more
details.   Without  pawproj=.true., the program calculates the partial
densities of states using a weight factor for an atomic pseudofunction
stored in the UPF file.    The results would be quantitatively different,
but (hopefully) qualitatively similar.

Sincerely, Natalie Holzwarth

N. A. W. Holzwarth                                       email:
natalie at wfu.edu
Department of Physics                                  web:
http://www.wfu.edu/~natalie
Wake Forest University                                 phone:
1-336-758-5510
Winston-Salem, NC 27109 USA                     office: Rm. 300 Olin
Physical Lab

On Thu, Apr 28, 2016 at 9:02 AM, Ifeanyi John ONUORAH <
ifeanyijohn.onuorah at studenti.unipr.it> wrote:

> Dear all,
>
> Using the projectors and all-electron PAW basis set to calculate weight
> factors for the PDOS,LDOS by setting the pawproj option == .true., say for
> hydrogen impurities in transition metals, give two contributions to the
> hydrogen s orbital with files in the form '...(H)_wfc#1(s)' and
> '...(H)_wfc#1(s)' i.e with wavefunction number 1 and 2. While without the
> pawproj option only one file for the hydrogen atom is given in the form
> '...(H)_wfc#1(s)'.
>
> I will appreciate if someone explains where these two contributions with
> the 'pawproj' are coming from. I tried to look at the pseudopotential file
> but it is not clear still,  I used this  H.pbe-kjpaw_psl.0.1.UPF on the
> quantum espresso webpage and QE version  5.3.0. Also, I will like to point
> that doing the integration of the difference of the ldos(up and down) till
> the fermi energy results with one file giving a negative contribution,
> while the other positive.
>
>
> Onuorah Ifeanyi J.
> PhD student,
> Department of Physics and Earth Sciences,
> University of Parma,
> Italy.
>
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> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
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