Thank you for reply, professor. I understand the regular routine implemented in QE where the long-range contribution is added in reciprocal space. My point is can I get the correct dynamical matrix just by making inverse Fourier transformation of the full(short+long) IFCs in a large real space?
The dynamical matrix at Gamma is discontinuity with respect to the points nearby, which would make any Fourier transform impossible to converge.
I think you should explain WHY you want to do this, and you may get some better answer.
In practice, if I was obliged at gunpoint, I would replace the dynamical matrix file at Gamma (typically dyn1) with one computed very close to Gamma, let's say q=0.001,0,0. Edit the file to trick q2r into thinking that it was done at exactly Gamma, and see was comes out.
If the material has a non-analytic term (i.e. the long range term depends on the direction), this will definitely not work. Otherwise, you may get something decent.
cheers -- Lorenzo Paulatto - Paris _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
