[Pw_forum] shape of the wave function in reciprocal space

[Jacopo Simoni]

Ok many thanks for the help

Best regards, Jacopo Simoni

On 26 May 2017 at 00:03, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:

> Yes
>
> On Fri, May 26, 2017 at 8:01 AM, Jacopo Simoni <simonij at tcd.ie> wrote:
> > Many thanks for the answer.
> >
> > This means that the G+k points written in the gkvectors.xml file are the
> > ones such that
> >
> > \hbar^2|k+G|^2/(2m) < Ecut
> >
> > and they form a sphere not a parallelepiped
> > I am right ?
> >
> > On 25 May 2017 at 23:49, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
> >>
> >> Only plane waves with \hbar^2(k+G)^2/(2m) < Ecut are included. The
> >> regular grid in G-space must be large enough to include all of them,
> >> but it also includes a significant amount of plane waves that exceed
> >> the cutoff.
> >>
> >> Paolo
> >>
> >> On Fri, May 26, 2017 at 2:46 AM, Jacopo Simoni <simonij at tcd.ie> wrote:
> >> > Dear PWSCF users,
> >> >
> >> > I am doing a simple scf calculation for a system of 100 Hydrogen atoms
> >> > in a
> >> > simple cubic cell.
> >> >
> >> > I am generating the wave functions with wf_collect=.true. for a
> single K
> >> > vector (0,0,0).
> >> >
> >> > From the scf output I realized that the total number of G vectors
> >> > printed on
> >> > the file is 847. I am using ecutwfc=20.0 and the shape of the
> Kohn-Sham
> >> > matrix is
> >> >
> >> > Kohn-Sham wave functions    dimensions=(847, 52)
> >> >
> >> > where 52 corresponds to the number of bands that I am using in the
> >> > calculation.
> >> >
> >> > However, I am wondering why in the gkvectors.xml file I have a list
> of G
> >> > vectors ranging between -5 and 5 times 2*pi / a (a is the lattice
> >> > parameter)
> >> > along each primitive lattice direction.
> >> >
> >> > The total number of points in such a regular grid should be 11*11*11 =
> >> > 1331
> >> > that is clearly different from 847. What is the meaning of the missing
> >> > 484 G
> >> > vectors in the grid ? I am a bit confused could you please explain to
> me
> >> > these results ?
> >> >
> >> > Many thanks in advance,
> >> >
> >> > Jacopo Simoni,
> >> > Los Alamos National Laboratory
> >> >
> >> > _______________________________________________
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> >> > Pw_forum at pwscf.org
> >> > http://pwscf.org/mailman/listinfo/pw_forum
> >>
> >>
> >>
> >> --
> >> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> >> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> >> Phone +39-0432-558216, fax +39-0432-558222
> >> _______________________________________________
> >> Pw_forum mailing list
> >> Pw_forum at pwscf.org
> >> http://pwscf.org/mailman/listinfo/pw_forum
> >
> >
> >
> > _______________________________________________
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> > http://pwscf.org/mailman/listinfo/pw_forum
>
>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
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