The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Ganesh,

The input below is definitely NOT Fm-3m.
One does not need a computer code to see this ... atoms 3 and 4 are  
NOT at a symmetric position.
You must have given another input to FINDSYM ?!
Or perhaps you have given a tolerance of more than one percent to  
FINDSYM ?!?

Xavier


On 21 Oct 2007, at 20:43, P. Ganesh wrote:

> I am having trouble with getting ABINIT to give the right space  
> group!!
>
> For example,  if I give the coordinates (listed below) into the  
> "FINDSYM" program (it is known to be a reliable source to find  
> symmetries.  one can google it) and select 'I' centering I get the  
> correct space-group I want (since I worked out the co-ords.), Fm-3m  
> (#225).  But ABINIT finds the spacegroup to be Pmm2 (#25) . So why  
> doens't ABINIT recognise the spcgrp. to be #225 ?  Do I need to  
> shift the origin to get the centering correct? I am not using any  
> symmetry variable, system is non-magnetic.
> Thank you in advance for any suggestions.
>
> Ganesh
>
>
> typat 1 2 3 3 4 4 4 4 4 4
>
> acell     7.09 7.09 14.18
> rprim     1.0 -1.0 0.0
>          1.0 1.0 0.0
>          0.0 0.0 1.0
>
> xred      0.0 0.5 0.25
>          0.0 0.5 0.75
>          0.0 0.0 0.01
>          0.0 0.0 0.51
>          0.25 0.25 0.0
>          -0.25 0.25 0.0
>          0.0 0.0 0.25
>          0.25 0.25 0.5
>          -0.25 0.25 0.5
>          0.0 0.0 0.75