ABINIT Discussion Forums

Dear Abinit users

I have been trying to obtain the ground state geometry of an isolated molecule. I modified the k-point grid definition in "trf1_1.in" for AlAs to the desired molecule as follows:
kptopt 0
nkpt 1

and used the ground state configuration obtained from that calculation for response function calculation of full dynamical matrix at the Gamma point. I used the following input variables for defining the k point grid.
kptopt 2
ngkpt 1 1 1
nshiftk 1
shiftk 0.0 0.0 0.0

My doubt is that whether I need to use the same k-point grid definition for the above two calculations or for all response function calculations.

Any help in this regard is greatly appreciated

Thanks in advance
Seba

Hi Seba,

for an isolated system there is never any need for k-points.

mverstra wrote:Hi Seba,

for an isolated system there is never any need for k-points.

Hai mverstra,

Thank you for the reply. But for my previous post on "How to calculate the phonon frequencies of an isolated molecule", you have replied to go ahead with k point definition as follows in the "trf1_4.in" for the isolated molecule:

kptopt 2
ngkpt 1 1 1
nshiftk 1
shiftk 0.0 0.0 0.0

So I am confused now on the k point definition in the input file.

Kindly guide me in this regard.

Thanks in advance
Seba

Yes - what I mean is: 1 kpt Gamma only is enough.