[Pw_forum] shape of the wave function in reciprocal space

[Paolo Giannozzi]

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
>> >
>> > _______________________________________________
>> > Pw_forum mailing list
>> > 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
>
>
>
> _______________________________________________
> Pw_forum mailing list
> 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