[Pw_forum] Regarding anharmonic IFCs

[david yang]

Dear Users and developers of Quantum espresso,
                               I have some question regarding D3 code .

I am interested in Anharmonic properties of crystals and for that i am
using D3 code of quantum espresso while going through the source code i
figured out that present version of quantum espresso calculates Anharmonic
IFCs only for q=0,q' and q" .
So that mean that quantum espresso  gives us anharmonic IFCs in reciprocal
space something like phi(0,q',q') where phi denotes anharmonic IFC.

I have two questions on this

(1)--Whether my understanding is correct?
(2)--For my work i need anharmonic IFCs in real space means phi(0,l,l')
I known that this can be done by taking inverse Fourier transform of
phi(0,q',-q') , but i am clue less after this .
Can anyone give me hint that how to proceed for inverse Fourier transform
...



I will be great-full to all of you.
Awaiting for responses



Thanks a lot





With warm regards
David yang
NTU
Singapore
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