On Mar 24, 2010, at 12:46 PM, Dimpy Sharma wrote:
> Hi there,
>
> I have submitted my input file for nscf calcuation with 22 kpoints ( for the
> first brilloiun zone from kpoint from k=0 to 0.47) however in the output file
> of nscf , it calcuates the eigenvalues at k points 0,0.148,0.2960..3.1076
> .Thus while plotting the band diagram my kvectir range becomes upto 3.1076.
> May I know why it happen? and to calculate the eigenvalues only on the given
> kpoints in th input file?
>
> Thanks
>
> Dimpy
>
> Dimpy Sharma(Msc Nanotechnology
> PhD)
> UCC
> Ireland
>
possible issues:
i) if the number of k-points in the output is greater than the number of
k-points you specify in the input, then the issue can be related
to symmetries. Unless you explicitly specify nosym = .true. (in nscf) the code
always "complete" the k-point list in such a way it gets
compatible with the symmetry operations
ii) you are just "reading" your k-points in different units than you expect.
Indeed, when the codes prints out the eigenvalues at each
k-point, the coordinates of the latter are tpiba, namely, 2 * pi / a (where a
is the lattice constant along the first direct lattice axis).
Therefore, if you give, in the input
K_POINTS {crystal}
0.0 0.0 0.5 1.0
then if the system is not cubic ad c is the lattice parameter along the third
direct lattice axis, the coordinates found in the output
will be 0.5 *a / c
I think that the band structure calculation requires not to keep the original
"crystal units", because if you want to compute the band structure
along a given path in the Brilluoin zone, you want to keep the relative
dimension of different segments (e.g. L-Gamma, Gamma-X) and for
that you cannot use a different unit along different directions (as it would
occur in crystal coordinates in non-cubic systems).
giovanni
--
Giovanni Cantele, PhD
CNR-SPIN and Dipartimento di Scienze Fisiche
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
Phone: +39 081 676910 - Fax: +39 081 676346
Skype contact: giocan74
ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele
http://www.nanomat.unina.it
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