[Wien] interface between WIEN2k and Wannier90

[Peter Blaha]

Simple crystallography:
 From your list at the end of your email I can see that the case you try has FCC symmetry.

An FCC lattice in direct space has BCC symmetry in reciprocal symmetry.

And yes, the first non-zero reciprocal lattice vector is (1,1,1)pi/a, but the next one is
(0,0,2)pi/a. Of course in such a lattice you do NOT have a reciprocal lattice vector (0,0,1),
since this does not point to a lattice point.
The lattice vector (0,0,1) exists only in Primitive lattices.

I'm not sure, but your mistake might happen, when you calculate the G-vector for
theta(Gi-Gj+G(k+b))

What is G(k+b) ??  If k and b are k-vector within the BZ (e.g. (0.1,0.15,0.25)), this
will NEVER make a FULL RECIPROCAL LATTICE vector (which always points to different origins
of the rec.unit cell). This might give you some additional phase factor (exp(i k+b r), but
for sure you cannot Fourier transform it.

fatemeh.mirjani schrieb:
> Dear Prof.Blaha;
> 
> I finished the writing of programs for interface code between WIEN2k and Wannier90 but there was a bug in my code which caused the wrong result. I searched for it and finally I found that the bug was in the theta(Gi-Gj+G(k+b)) (FFT of the step-function : theta(r)).
> 
> M_mn(k,b) at interstitial region = sigma_Gi,Gj{ c*(k,m)_Gi  c([k+b],n)_Gj  theta(Gi-Gj+G(k+b))  }
> 
>  "where G(k+b) denotes the reciprocal space vector that moves (k+b) into the first brillouin zone, [k+b]=k+b-G(k+b)."
> 
> I extracted theta(G) from Wien2k with the method which I have explained at the end of Email.
> Unfortunately with the used method I cannot extract theta for all of the "Gi-Gj+G(k+b)" vectors. so automatically when the program couldn't extract theta(Gi-Gj+G(k+b)) for a special "Gi-Gj+G(k+b)" it put it's amount equal to zero.
> 

> for example I should find theta(G= 0  0 -1)
> but the file which is consist of theta(G) is like this:
>   0.0000000E+00  0.0000000E+00  0.0000000E+00 (176.097523798869,0.000000000000000E+000)
>   -1.000000      -1.000000      -1.000000     (34.5063794979096,0.000000000000000E+000)
>    1.000000       1.000000      -1.000000     (-34.5063794979096,0.000000000000000E+000)
>    1.000000      -1.000000       1.000000     (-34.5063794979096,0.000000000000000E+000)
>   -1.000000       1.000000       1.000000     (-34.5063794979097,0.000000000000000E+000)
>   -1.000000      -1.000000       1.000000     (-34.5063794979096,0.000000000000000E+000)
>    1.000000       1.000000       1.000000     (34.5063794979096,0.000000000000000E+000)
>    1.000000      -1.000000      -1.000000     (-34.5063794979097,0.000000000000000E+000)
>   -1.000000       1.000000      -1.000000     (-34.5063794979096,0.000000000000000E+000)
>   0.0000000E+00  0.0000000E+00  -2.000000     (2.370408305436463E-015,0.000000000000000E+000)
>   0.0000000E+00  0.0000000E+00   2.000000     (2.370408305436463E-015,0.000000000000000E+000)
>   0.0000000E+00  -2.000000      0.0000000E+00 (2.370408305436463E-015,0.000000000000000E+000)
>   ...
>   ...
>   ...
>   ...
> so I don't know the amount of theta(G= 0  0 -1)
> 

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
--------------------------------------------------------------------------