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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Since
A1 = (1/3) A2
B1 = (1/3) B2
C1 = (1/3) C2
I would say that the k-point with the same position in the original
cell as 3A2+6B2+ 9C2  is
9 A1 + 18 B1 + 27 C1

A simple way to test all this arithmetic would be  (for instance) to
draw the band structure from Gamma(000) to Gamma(111) in both your
simple and multiple cell. At the end you will decide more easily What
k-points you need.



On Tue, May 13, 2008 at 2:02 AM, Andrey Chibisov
<andreichibisov@yandex.ru> wrote:
> ...So if new basis as 3A2+6B2+ 9C2 (for Si 3x3x3 cell) then k-point 
> coordinates of unit cell Si must be decrease so as 
> (1/3)A1+(2/3)B1+(3/3)C1...?
>
>
>  Is it some paper about converting of k-point coordinates from unit cell to 
> supercell (2x2x2 or 3x3x3)?
>
>
>  05.05.08, 11:18, "Anglade Pierre-Matthieu" <anglade@gmail.com>:
>
>
>  > Hi,
>  > I'm quite not sure do understand your question and what you want to
>  > do. However If you use a cell that is 3x3x3 of an other cell where you
>  > know which k-points you want to use, and if you want to use the same
>  > k-points you use in the small cell, do the following:
>  > - notice the coordinates of your previous k-ponts. This are
>  > coordinates in reciprocal space given in multiple of the primitive
>  > vectors of your cell
>  > - convert those coordinates in the new basis given by your new
>  > reciprocal space vectors.
>  > For instance, lets call a1, b1, c1 your unit cells basis vectors ;
>  > a2, b2, c2 the increased vectors (such that a2=3xa1 ...) and denote
>  > with capital vectors the reciprocal space vectors:
>  > you have A1= b1Xc1/(a1.b1Xc1) and A2=b2xc2/(a2.b2Xc2) so A2=A1/3,
>  > etc... If a k-point corrdinates were 1A1+2B1+3C1 they can simply be
>  > express in the new basis as 3A2+6B2+ 9C2...
>  > Hope this help...
>  > regards
>  > PMA
>  > On Sun, May 4, 2008 at 4:14 AM, Andrey Chibisov
>  > <andreichibisov@yandex.ru> wrote:
>
>
> > > Hello, Dear colleagues!
>  > >  I'm new user.
>  > >  How defined k-poin for Si 3x3x3-cell or 3x3x3-cell ? To define 
> correct band gap?
>  > >
>  > >
>  > >  --
>  > >  Andrey Chibisov.
>  > >  Structural Ceramics Laboratory
>  > >  Institute of Geology and Nature Management
>  > >  Far Eastern Branch of Russian Academy of Sciences
>  > >
>  > >
>
>  --
>  Andrey Chibisov.
>  Candidate of Science,
>
> Structural Ceramics Laboratory
>  Institute of Geology and Nature Management
>  Far Eastern Branch of Russian Academy of Sciences
>
>
>
>  Яндекс.Фотки - легко загрузить с мобильного http://mobile.yandex.ru/fotki/
>



-- 
Pierre-Matthieu Anglade