[Wien] c(G)_k,m in FFT-mesh

[Peter Blaha]

You can use c(G) from output1 (limited accuracy!!) or case.vector.

In the general case, you will not have any symmetry, so forget "stars" 
(assume you have only the identity symm.op.)

In any case your
  M_mn interstitial(k1,k2)=<u_m,k1|u_n,k2>= sigma_ij{c*_m,k1(Gi) * 
theta(Gi-Gj) *  c_n,k2(Gj)}

is something like a "density" (product of two (different) wavefunctions) 
and almost everything (besides a phase factor from (k2-k1) can be 
handled as in lapw2 (fourier). The resulting "density" can be plugged 
into a modified "lapw0" to reanalyse with the stepfunction.

Of course one can modify the FFT mesh in lapw0. Read the UG.

> I was going to use the c(G) coefficients in case.output1 but according to your explanation, I understood I cannot use the G-Stars set for this purpose (using symmetry).
> In order to extract the complete list of c(G) coefficients, you said expansion and contraction is done by setfft and getfft. but I couldn't find the variable which is equivalent to c(G). I should extract all the c(G) coefficients for all kpoints and all bands (c(G)_k,m ). Where can I find them and print them for all kpoints and all bands?
> 
> Another point is a very dense FFT-mesh.To avoid using this mesh, Is it true to change the number of G-vectors (NKK) in lapw0.F manually?
> 
> Your help is appreciated.
> 
> With my best regards,
> Fatemeh  

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Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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