[Pw_forum] strange number of kpoints

[Javad hashemifar]

Thanks Stefano for your answer. yes I was using 1 1 1 as shift
parameters and when I changed it to 0 0 1 the irreducible number of
kpoints substantially reduced to 770/2=385

Many thanks again to you and Eyvaz
Javad Hashemifar

On 2/5/07, degironc <degironc at sissa.it> wrote:
> Dear Javad hashemifar,
>
>     what is the k-point grid that you specified ?
>     10 10 14 1 1 1 ? try instead 10 10 14 0 0 1
>     In an hexagonal crystal  it is usually convenient to use unshifted
> grids in the hexagonal plane.
>
>      hope it helps
>      stefano
>
> Javad hashemifar wrote:
>
> > Thank you for your answer. After your answer I checked the klist and
> > realized that each kpoint is repeated twice. So now I suppose that the
> > number of irreducible kpoints is 2170/2=1085 that is very close to the
> > total number of kpoints ~ 10x10x14=1400. While based on the 8 symmetry
> > operation that my system has (4+inversion), I would expect that the
> > number of irreducible kpoints should be much lower than the total
> > number of kpoints. Would you please let me to know your comment on
> > that.
> >
> > Javad Hashemifar
> >
> >
> > On 2/5/07, Eyvaz Isaev <eyvaz_isaev at yahoo.com> wrote:
> >
> >> Hi,
> >>
> >> As far as I know number of k-points is doubled for magnettic
> >> calculations, so there is nothing to be surprized.
> >>
> >> Bests,
> >> Eyvaz.
> >>
> >> ----- Original Message ----
> >> From: Javad hashemifar <jhashemifar at gmail.com>
> >> To: pw_forum at pwscf.org
> >> Sent: Monday, February 5, 2007 6:45:47 PM
> >>
> >> Dear Espresso users
> >>
> >> I am calculating CrAs in the hexagonal NiAs structure and in order to
> >> study different types of antiferromagnetic arrangement, the in plane
> >> lattice parameters (a,b) are doubled. I am using an "automatic" k-mesh
> >> of 10x10x14 while the output number of (irreducible) k-points are:
> >>
> >> number of k points= 2170
> >>
> >> It is strange to me because I expect that the number of kpoints in the
> >> irreducible wedge of the BZ should be less than the total number of
> >> kpoints that I think should be around 10x10x14 = 1400 points.
> >> I searched the archive but unfortunately did not find any answer and
> >> so your comments in this regard is highly appreciated.
> >>
> >> This system has 4 Sym.Ops. (with inversion).
> >>
> >> Thanks in advance
> >> Javad Hashemifar
> >>
> >>
> >>
> >> ======================================
> >> Seyed Javad  Hashemifar,    Ph.D.
> >> [current:]
> >> Tel:+49-203-3794743        Fax:+49-203-3794742
> >> Fachbereich Physik (AG Kratzer), Universitat Duisburg-Essen
> >> 47048 Dusiburg, Germany
> >> [permanent:]
> >> Tel:  +98-311-3912375       Fax: +98-311-3912376
> >> Physics Department, Isfahan University of Technology
> >> 84156 Isfahan, Iran
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-- 
======================================
Seyed Javad  Hashemifar,    Ph.D.
[current:]
Tel:+49-203-3794743        Fax:+49-203-3794742
Fachbereich Physik (AG Kratzer), Universitat Duisburg-Essen
47048 Dusiburg, Germany
[permanent:]
Tel:  +98-311-3912375       Fax: +98-311-3912376
Physics Department, Isfahan University of Technology
84156 Isfahan, Iran
---------------------------------------------------------------------------