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
_______________________________________________________________________________
The Quantum ESPRESSO Foundation stands in solidarity with all civilians
worldwide who are victims of terrorism, military aggression, and indiscriminate
warfare.
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