ABINIT Discussion Forums

Dear Abinit users,

I am trying to calculate the phonon frequencies of an isolated molecule. I followed the tutorial response-function 1 and used trf1_4.in file to obtain the phonon frequencies at Gamma. I modified the common input variables in trf1_4.in which corresponds to a crystalline AlAs according to the molecule that I need. Can I modify the k-point grid definition as follows:
kptopt 2
ngkpt 1 1 1
nshiftk 1
shiftk 0.0 0.0 0.0

Is these values correct for the response function calculation of an isolated molecule.

Any comments in this regard are greatly appreciated.

Thanks in advance
Seba

yes, this is fine. Same for q, only 0 0 0 is needed. The default shiftk 0.5 0.5 0.5 is a pain, and you should indeed compensate it, but it's not a big deal even if you leave the default: all the bands will be flat if your vacuum is well converged.