The ABINIT Users Mailing List ( CLOSED )

["P. Ganesh" <pganesh@ciw.edu>]

The values for the 3rd and 4th atom are:

0.0 0.0 0.00
0.0 0.0 0.50

Sorry about the misprint in my email (I was also trying for tetragonal 
distortions as well and hence the mixup).  But the problem remains the 
same.  ABINIT does not recognise the now corrected coordinates to be 
Fm-3m (or recognise it to be I4mm with the distortion of 0.01 in reduced 
coordinates of the 3rd and 4th atom as entered below).   Findsym 
recognises them to be so if I select them to be I centered.

Thanks,

Ganesh





Xavier Gonze wrote:
> 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