[Pw_forum] symmetry of defect state

[Gabriele Sclauzero]

Dear Ali,

ali kazempour wrote:
> Hi
> Does anyone knows how to determine the symmetry of  the defect state 
> introduced in gap or how to join the the relaxation of atoms around the 
> defect  by the  changing point group?

Honestly, your question is not much clear to me (and maybe also to the others, since you 
received no reply yet), but I would like to help you to make it more specific.

What symmetry do you want to determine? The symmetry of a specific KS eigenstate, or the 
point group of a system after removing an atom to create a defect?
In the first case you can use the program bands.x with lsym=.TRUE., in the second it is 
done automatically by pw.x at the beginning of the run (if you specify verbosity='high' it 
will also print all symmetry operations belonging to the point group).

I think that if you introduce a defect and you want to relax your structure, you should 
slightly, randomly displace some atoms near the defect in order to further reduce the 
symmetry and allow atomic coordinates to span a larger phase space to reach a better 
minimum. Remember that very large supercells may be needed in these kind of studies.

HTH,

GS


> thanks a lot
>  
> Ali Kazempour
> Physics department, Isfahan University of Technology
> 84156 Isfahan, Iran. Tel-1: +98 311 391 3733
> Fax: +98 311 391 2376 Tel-2: +98 311 391 2375
> 
> 
> 
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