[Wien] overlap matrix at the interstitial region and using FFT

[fatemeh.mirjani]

Dear Prof.Blaha;

I'm writing an interface between Wien2k and Wannier90 codes.
The only quantity which has remained in calculations is the overlap matrix at the interstitial region. I used FFTW libraries for calculating the Fourier Transform of step-function ”theta(r) “. The step-function is zero in the Muffin-Tin spheres and is equal to 1 at the interstitial region. I designed a 100*100*100 mesh for unit-cell and defined the theta(r) in this mesh. “theta(G)” is the answre of Fourier transform where G is the reciprocal lattice vector. But after writing a program (by using FFTW libraries) and getting the result, I don’t know each theta(G) is belonged to which G ?
 
So, I searched for the solution. According to my search I found 2 points.
1- using FFTW libraries is not a safe method in this way. (Since the real-space is tarnsfered to G-space.)
2-  I think the overlap matrix is calculated in Wien2k certainly. but I don't know where I should find it?
Would you please guide me in which program of the source of Wien2k I can find this overlap?
(I have sent the integral file for your observation.)


Your help is appreciated like your previous favor.

With my best regards,
Fatemeh
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|Fatemeh Mirjani                              | Email: f_mirjani at ph.iut.ac.ir  |
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