The ABINIT Users Mailing List ( CLOSED )

["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hello,

nshiftk 4 will make 4 grid shifted from each others by one of the
provides "shiftk" vector.
Nhsiftk 1 will make a single grid shifted by the single provided shiftk 
vector.
The purpose of shiftk is to allow simpler input for some special,
highly efficient k-point grid.
Combining multiple shiftk with ngkpt you can specify any regular grid
you can imagine.
The other way to do that is to use a single shiftk and "kptrlatt".
This provide you also the ability to specify any regular kpoint grid.
For beginners and other people like me who are not able to guess the
best k-point grid by simply knowing the space group Abinit provide a
quite convenient input variable called "prtkpt". Used in combination
with "kptrlen" it will tell you the parameters you shall input to get
the best possible k-point grid.

Regards

PMA

On Fri, Mar 21, 2008 at 2:03 AM,  <jjr19@uakron.edu> wrote:
> In the documentation for shiftk, multiple k-point shifts are recommended 
> for certain kinds of lattices, and from a brief look at the ABINIT code, 
> all these shifts seem to be added to a k-point more or less one right after 
> the other, with some sort of normalizing (?) done after each shift. I'm not 
> sure though what the difference is supposed to be between this:
>
>  nshiftk 4
>  shiftk 0.5 0.5 0.5
>       0.5 0.0 0.0
>       0.0 0.5 0.0
>       0.0 0.0 0.5
>
>  and this:
>
>  nshiftk 1
>  shiftk 1.0 1.0 1.0
>



-- 
Pierre-Matthieu Anglade