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[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

Yes, you need at least a 2x2x2 k-point grid to calculate the Berry
phase. This was also mentioned in a forum post a week or two ago.

Matthieu

On Mon, Mar 30, 2009 at 4:37 PM,  <6671011@163.com> wrote:
> Dear friends,
>
>    While calculating the Raman spectra of molecule H2O with only Gamma 
> kpoint,
> I found the non-linear DATASET failed with the following output.
>
> ----------------------------------------------------------------------------------------
>  nonlinear : nkpt, nkpt3 =            1           1
>  getkgrid : length of smallest supercell vector (bohr)=    7.445834E+00
>       Simple Lattice Grid
>  nonlinear : nkpt, nkpt3 =            1           1
>  getkgrid : length of smallest supercell vector (bohr)=    7.445834E+00
>       Simple Lattice Grid
>
>  getshell: BUG -
>  Cannot find enough neighbor shells
>  Action : contact ABINIT group.
> ----------------------------------------------------------------------------------------
>
>    To overcome this problem, I need to use more kpoints, such as ngkpt 2 2 
> 2.
> So, does it mean that the non-linear RF does not support a single kpoint
> calculation?
>
>  P.S. I tested it in both Abinit 5.6.4 and 5.7.3. (You can repeat this 
> problem
> by changing the kpoint parameters in the build-in test file tnol_2.in)
>
> Sincerely,
> Guangfu Luo
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF)
Dpto. Fisica de Materiales,
U. del Pais Vasco,
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500