[Pw_forum] Density of states

[Eyvaz Isaev]

Dear Padmaya,

--- On Fri, 11/6/09, Padmaja Patnaik <padmaja_patnaik at yahoo.co.uk> wrote:
> 
> I am working on semiconductors with impurities and
> calculating with quantum espresso code. The density of
> states plot for  unrelaxed condition shows the band gap and when relaxed > the  plot shows  no band gap (please refer to the attached file). Is this
> enough to tell  that its half-metallic after relaxation? 

No, because it is absolutely not related with the half-metallic systems (at least what you have shown). Please have a look at the web page:

http://en.wikipedia.org/wiki/Half-metal

to understand what is "Half-metallic system". And then look at your DOS pictures to figure out what do you have, metallic or half-metallic system.

>Or do i have to  look at some
> other values also? If yes what should i look at. 

Looking at your DOS pictures it is quite strange to see  that after relaxation the DOS is completely different from the original one. Yes, usually some extra bands (in the band gap) appear due to relaxation (lowering the symmetry), nevertheless it almost conserves the shape of the original (unrelaxed) DOS.
So, it seems in your calculations something went in the wrong  way.

Bests,
Eyvaz.
P.S. Please avoid repeating a message to the forum, this will not give you more chance to get a reply. 

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com