The ABINIT Users Mailing List ( CLOSED )

[ren <opticalcase@gmail.com>]

Dr Matthieu:

Thank you very much for your advices!!!! I will go ahead with my
calculation now!

Cheers,
Yee Yan

On Fri, Feb 27, 2009 at 6:48 PM, Anglade Pierre-Matthieu
<anglade@gmail.com> wrote:
> Hi,
>
> Yes in this case "chkprim 0" is the keyword to use. However you can
> also "guess" the total energy of the 2x2x2 perfect supercell without a
> vacancy/impurity/etc from the single cell calculation. Both ways are
> correct. Yet in your case since you will perform the supercell
> calculation anyway you can just forget about my comment and go ahead
> with chkprim=0.
>
> regards
>
> PMA
>
> PS:I'm no prof.
>
> On Fri, Feb 27, 2009 at 9:53 AM, ren <opticalcase@gmail.com> wrote:
>> Dear Prof Matthieu:
>>
>> Thank you for your quick reply! My apology, if I interpret correctly
>> what you are saying, is that for my calculation of a 2x2x2 supercell,
>> i will get the same result as a 1x1x1 unit cell except that since
>> 2x2x2 supercell is much larger, the computational cost would scale to
>> more than 8^3?
>>
>> I am making a 2x2x2 supercell as a starting point as I am considering
>> vacancy in my material in the future. I read your post in the past in
>> the forum, suggesting to someone that in considering a supercell (for
>> a vacancy) e.g, chkprim=0 must be use? Please correct me if I am
>> wrong?
>>
>> Regards,
>> Yee Yan
>>
>>
>>
>> On Fri, Feb 27, 2009 at 1:23 AM, Anglade Pierre-Matthieu
>> <anglade@gmail.com> wrote:
>>> 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
>>>
>>>
>>
>>
>
>
>
> --
> Pierre-Matthieu Anglade
>
>