The ABINIT Users Mailing List ( CLOSED )

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

Hi,

The transformation apparently keeps the 2x2x2 supercell.
In most case it is not appropriate to input chkprim =0 since you will
get essentially the same results has using a single cell but at
much more than 8 to the power three times the computational cost. Yet,
for a converged calculation you'll get the same properties.

regards

PMA


On Thu, Feb 26, 2009 at 3:48 PM, ren <opticalcase@gmail.com> wrote:
> Dear All,
>
> I am using Cell2Abinit.py to transform a 2x2x2 supercell of ZnO from
> Castep to Abinit format. I suppose that the transformation creates a
> primitive cell? The problem occurs when I am trying to run Abinit, the
> calculation halt and the log file says
>
> " According to the symmetry finder, the unit cell is
>   NOT primitive. The multiplicity is  8 .
>   The use of non-primitive unit cells is allowed
>   only when the input variable chkprim is 0.
>   Action : either change your unit cell (rprim or angdeg),
>   or set chkprim to 0. it says that the input structure is not a
> primitive cell and has a multplicity of 8."
>
> While I input chkprim = 0 and the calculation continues run may I know if
>
> 1) It is appropriate just to simply use chkprim = 0
>
> 2) Is there something i have miss out while using Cell2Abinit that the
> output is not a primitive cell in the end? My structure input is as
> below:
>
> ####################################################
> # Atoms Stucture created by CellToAbinit Converter !
> ####################################################
>
> # Definition of the unit cell
> #The length of the primitive vectors
> #                    1 Bohr=0.5291772108 Angstroms
> # acell 5.627901 6.498540 10.410880 Angstroms
> acell 10.635191 12.280461 19.673712
> rprim
>     1.000000  -0.577350  0.000000
>     0.000000  1.000000  0.000000
>     0.000000  0.000000  1.000000
>
> #Definition of the atom types
> #      32 kind of atoms
> #       ['O', 'Zn']
> ntypat  2
> znucl  8 30
>
> #Definition of tha atoms
> natom  32
> typat  1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
> xred
>    0.166667 0.333333   0.1913
>    0.333333 0.166667   0.4413
>    0.666667 0.333333   0.1913
>    0.833333 0.166667   0.4413
>    0.166667 0.833333   0.1913
>    0.333333 0.666667   0.4413
>    0.666667 0.833333   0.1913
>    0.833333 0.666667   0.4413
>    0.166667 0.333333   0.6913
>    0.333333 0.166667   0.9413
>    0.666667 0.333333   0.6913
>    0.833333 0.166667   0.9413
>    0.166667 0.833333   0.6913
>    0.333333 0.666667   0.9413
>    0.666667 0.833333   0.6913
>    0.833333 0.666667   0.9413
>    0.166667 0.333333      0.0
>    0.333333 0.166667     0.25
>    0.666667 0.333333      0.0
>    0.833333 0.166667     0.25
>    0.166667 0.833333      0.0
>    0.333333 0.666667     0.25
>    0.666667 0.833333      0.0
>    0.833333 0.666667     0.25
>    0.166667 0.333333      0.5
>    0.333333 0.166667     0.75
>    0.666667 0.333333      0.5
>    0.833333 0.166667     0.75
>    0.166667 0.833333      0.5
>    0.333333 0.666667     0.75
>    0.666667 0.833333      0.5
>    0.833333 0.666667     0.75
>
> ##### End of CellToAbinit Conveter ! #####
>
> The calculation runs well for a 1x1x1 and 3x3x3 cell without such
> these comment though.
>
> Would like to hear your advises!
>
> Regards,
>
> Yee Yan, Tay
>
> Nanyang Technological University
>
> Singapore
>
>



-- 
Pierre-Matthieu Anglade