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

[Holzwarth, Natalie]

Dear  Ifeanyi J.,
      I am not sure if the individual terms are very meaningful.    They
should depend on the shapes of the basis and projector functions that were
generated for the particular UPF dataset that you are using.    The sum of
them however should be more robust.   Note that the sum approximates the
charge in a sphere around the H that has the radius of the so-called
augmentation sphere about the atom.

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 10:08 AM, Ifeanyi John ONUORAH <
ifeanyijohn.onuorah at studenti.unipr.it> wrote:

> Dear Holzwarth,
> Thank you for the note it has already helped a lot. Using the pawproj and
> adding the two contributions give very good results when compared with
> experimental results for my calculations. I am still trying to understand
> while one of the contributions is always positive and the other negative.
> If it depends on the assigned occupation of each of the two projector and
> basis function for the H s channel?
>
> Thank you
>
> Onuorah Ifeanyi J.
> PhD student,
> Department of Physics and Earth Sciences,
> University of Parma,
> Italy.
>
> 2016-04-28 15:33 GMT+02:00 Holzwarth, Natalie <natalie at wfu.edu>:
>
>> 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.
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://pwscf.org/mailman/listinfo/pw_forum
>>>
>>
>>
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