[Pw_forum] Details of partial density of states calculation
Holzwarth, Natalie
natalie at wfu.edu
Tue May 14 22:26:03 CEST 2013
Dear Stefano and Lorenzo,
Thanks for your emails. There are actually 2 threads to my
email. The first is to understand what is coded now and the second is to
add something in addition to the code if it is desired. On the first
point, you say the projection is onto the reference atomic functions, but I
could not figure out which functions from the PAW dataset were being taken
for this projection. From "reading" the code It looks like it the beta
functions which are in fact the projectors. I am not sure if this is
true and/or if these functions are renormalized in some way. Or perhaps
it is a different function that is taken for this.
About calculating the partial charges on the basis of the charge in
the augmentation charge, I will be glad to help if that is convenient. In
addition to terms in the augmentation sphere there would be a contribution
from the plane wave expansion (or pseudo wave) portion of the wavefunction.
What we did in the past is to just calculate the charge within the sphere
by integrating the Bessel function expansion of the pseudo density for that
state. If you want to keep the l-components it would be necessary to
modify that pseudo term according to their l-components. Of course there
are other (perhaps more simple) ways to do this. In principle, this is
not hard, but I would need to understand to code better....
Thanks, Natalie
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 Tue, May 14, 2013 at 3:47 AM, Stefano de Gironcoli <degironc at sissa.it>wrote:
> Dear Natalie, Dear Lorenzo
>
> the code projwfc calculate the projection of the crystal
> wavefunctions on the reference atomic wavefunctions of each atom in
> the cell (after these have bee orthogonalized). as such it strongly
> depends on which atomic wavefunctions are included in the reference
> computation in the atom.
>
> especially in the case these are extended orbitals (like the s-wave
> valence states of transition metals) the projections may not be very
> useful as a way to decompose the dos in atomic contributions.
>
> I think what you suggest, if i understand it correctly, can be a
> useful alternative:
> computing the amount of charge inside the sphere that can be
> assigned to the different angular momentum channels using the PAW
> reconstruction. the piece of information needed, in addition to the
> becp=<beta_a|psi> are the integrals of the corresponding atomic pseudo
> wavefunctions <phi_a|phi_a>_R or <phi_tilte_a|phi_tilde_a>_R+Q_aa
> where phi_a and phi_tilde_a are the AE and PS atomic wavefunctions
> respectively and Q_aa is the integral of the augmentation charge and
> the integrals are limited to the core region inside a radius R.
> something like that...
>
> stefano
>
>
> Quoting "Holzwarth, Natalie" <natalie at wfu.edu>:
>
> > Dear Lorenzo,
> >
> > Thanks for your answer. I can understand that projwfc may not
> > know about PAW, but the code apparently calls calbec which seems to
> > calculate the radial integral about an atom <beta|psi> where presumably
> > beta is obtained from the pseudopotential file??? Perhaps this
> internal
> > code notation is not consistent with the UPF file? On the other hand,
> if
> > the notation is consistent, then the beta term in the UPF file is the
> > projector for PAW (I think -- or at least that is true for ATOMPAW).
> > This is the reason for my assumption that <p^a_i|\psi> is calculated to
> > determine the partial density of states. I am trying to write a paper
> > with some pdos plots and wanted explain what the code does. It seems
> > like my suggestion to provide another option for the code would be a bit
> of
> > work so perhaps can wait. In any case, it is always good to know what
> has
> > been calculated.... Thanks in advance for any further
> > suggestions/discussion. Natalie
> >
> > 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 Mon, May 13, 2013 at 5:14 PM, Lorenzo Paulatto <
> > lorenzo.paulatto at impmc.upmc.fr> wrote:
> >
> >> On 05/08/2013 06:43 PM, Holzwarth, Natalie wrote:
> >>
> >> > It slightly worries me that the pdos defined in this way is fairly
> >> > sensitive to the PAW dataset used. I am having a debate with myself
> >> > about whether it might be good to append a piece of code I wrote long
> >> > ago to your code to calculate <p^a_i|\psi> and calculate a better
> >> > estimate of the charge inside the augmentation sphere. (Assuming it
> >> > would be possible to figure out the details of that code.) I welcome
> >> > your advice and commentary.
> >> >
> >> Dear Natalie,
> >> if I remember correctly, the PDOS code is not PAW-aware, i.e. it
> >> projects on pseudo atomic wavefunctions that it can find in the
> >> pseudpotential, completely ignoring the PAW projectors and stuff. It
> >> should depends on the dataset only if the reference configuration is
> >> changed, but it is true that nobody probably checked it properly.
> >>
> >> On the other hand, there is a code that reconstructs the PAW charge
> >> (it's pawplot.f90 in the PP/src directory), I do not know if it has
> >> anything in common with what you did. I'll have a look at it if you
> >> wish, if it improves prowfc it is of course welcome.
> >>
> >> bests
> >>
> >>
> >>
> >> --
> >> Dr. Lorenzo Paulatto
> >> IdR @ IMPMC -- CNRS & Université Paris 6
> >> phone:+33 (0)1 44275 084 / skype: paulatz
> >> www: http://www-int.impmc.upmc.fr/~paulatto/
> >> mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 5
> >>
> >> _______________________________________________
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> >>
>
>
>
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