[Pw_forum] DOS calculation with an Extra electron on a given atom

[Eyvaz Isaev]

Dear Nand,

>I have been doing DFT calculations on a GaAs supercell with a  substitutional 
>Mn.I would like to find the >acceptor(and Doner) energy of  Mn atom 
>


I suppose, you should read a textbook, say, R.Martin's Electronic Structure: 
Basic Theory and Practical Methods; review paper by Payne et al.RevModPhys, 64, 
1045; textbook by Kohanoff, Electronic structure calculations for solids and 
molecules, Ashcroft-Mermin's textbook, and there are many many  good textbooks 
on solid state physics, please do search in your University library) before 
doing such kind non-trivial calculations.

>acceptor(and Doner) energy of  Mn atom

"Doner" is absolutely different thing (in fact, it is  Turkish fast-food), but 
you mean "donor", obviously.

> I could not figure out how to do the DOS and PDOS calculations with an extra 
>electron on (or an >electron removed from) the  Mn atom.  
>

Well, this one can be done with tot_charge or nelec  parameters in scf file. 
See  INPUT_PW.txt  file in /DOC. Then do DOS and PDOS calculations, and compare 
with ideal GaAs results (bands structure, DOS and PDOS).  You will see a 
difference.

>I would like to learn how the removal of an electron from a supercell  of 17 
>atoms (with one Mn at the >centre) would solve my purpose of  finding the 
>(doner)energy.

Sorry, this is unclear. What is "donor energy"?  I would recommend  also reading 
a textbook (or a chapter) with describing semiconductors properties.  


> Is it that the hole will get localised on Mn.

Nobody can tell you about that as in DFT you can not put  a charged position in 
your input file. If you remove/add electrons, then other electrons will be 
redistributed during SCF calculations. An excess/deficiency of electrons  leads  
to uncompensated  Columb interaction. In order to avoid this (i.e. to make a 
system be neutral) a compensating jellium charge is automatically added by the 
program. So, you should not take care about this. 

Rather, you should take care about interpreting of  input data and results. 

You can see atomic charges  as a result of  PDOS  calculations and find whether 
there is a charge excess/depletion on atoms. 


>Secondly,  what is the "compensating gellium" (mentioned in input_PW.HTML doc)to  
>remove the >divergence and how is this incerted. 
>

See above.

>Your help is highly  appriciated.

Reading any good solid state textbook is also appreciated.  

Bests,
Eyvaz.
-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, 
Sweden 

Theoretical Physics Department, Moscow State Institute of Steel & Alloys, 
Russia, 

isaev at ifm.liu.se, eyvaz_isaev at yahoo.com


________________________________
From: nand <rana_nand at yahoo.com>
To: pw_forum at pwscf.org
Sent: Thu, August 5, 2010 9:27:29 PM
Subject: Re: [Pw_forum] DOS calculation with an Extra electron on a given atom 
(Stefano Baroni)


Dear Stefano,
Thanks a lot for your reply.
Thanking you.

Nand
Ranchi University
India



just do it. run the the code with one electron less, and adopt the usual 
precautions to deal with a charged cell. SB

On Aug 4, 2010, at 6:39 PM, nand  wrote:

> Dear Users,
> I have been doing DFT calculations on a GaAs supercell with a substitutional 
>Mn.I would like to find the acceptor(and Doner) energy of Mn atom however, I 
>could not figure out how to do the DOS and PDOS calculations with an extra 
>electron on (or an electron removed from) the  Mn atom. Plz some one guide me 
>for this.
> Thanking you all
> Nand Rana
> (Research Scholar)
> Ranchi University
> India
> 
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum

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