[Pw_forum] Some confusions with the crystal lattice vectors

[max]

Hello Dears,

I have some confusions about how quantum espresso manage the cells vectors.
Recently I used cif2qe to get positions of atoms from cif file. In the
output I read that:

! Found by cif2qe: lattice = cubic    Space group = Fd-3m   ibrav = 2

My structure is fcc the above is correct. But in cell paramaters that
cif2qe gave me:

CELL_PARAMETERS bohr
    15.571154294    0.000000000    0.000000000
     0.000000000   15.571154294    0.000000000
     0.000000000    0.000000000   15.571154294

But in Doc/INPUT_PW the vectos for fcc are:

2          cubic F (fcc)
      v1 = (a/2)(-1,0,1),  v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)

I not sure if this two input method are the same. Are there the same?

In same way in Solid State Physics books (like Kittel) refer to primitive
vectors fro fcc crystal, like this:

a_1 = (a/2)(x +y) ;          a_1 = (a/2)(y + z) ;        a_1 = (a/2)(z + x)

Are this vectores  the same that in Quantum Espresso Doc are referred like
crystal lattice vectors?

Any help will be grateful!
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20150813/d5767833/attachment.html>