[QE-users] The real space wavefunction by wfck2r.x

[Paolo Giannozzi]

If I remember correctly, real-space wavefunctions produced by FFT are 
normalized as follows:
    {1\over N_1 N_2_ N_3} \sum_{i=1}^{N} \psi_n^*(r_i)\psi_m(r_i) = 
\delta_{n,m}
where r_i are the points of the FFT grid, N=N_1 N_2 N_3 is the number of 
such points.

Paolo

On 6/13/25 15:09, Yuvam Bhateja via users wrote:
> Dear experts,
> I am trying to convert the reciprocal space wavefunction to real space 
> with the code I wrote, and the shape looks good and matches the input 
> unit cell. Later, I found out that there is a QE program that does the 
> same thing, wfck2r.x. However, upon comparing, I observed that my 
> converted wavefunction is 100 times lower than that of wfck2r.x. In my 
> code, I have used the same subroutines waveg2r and invfft as were used 
> in wfck2r.x, with an additional explicit renormalisation which was 
> missing in the source code of wfck2r.f90.
> I wanted to know if the wave function produced by wfck2r.x is already 
> normalised (perhaps within the invfft or waveg2r)? And does it need 
> to be renormalised to further use it in a calculation?
> 
> Best,
> Yuvam
> 
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine Italy, +39-0432-558216