[Pw_forum] supercell

[Giuseppe Mattioli]

Dear Halima
DFT+U is indeed a possible solution in order to have decent IE and EA values and, therefore, something resembling a correct band gap. But you should 
obtain a reduced gap (something around 1.0 eV) also with your standard GGA approach, unless, and this is your case, you are simulating something VERY 
far from the GaN wurtzite structure... Open your file with a visualization program (e.g., xcrysden), and you will spot the problem at once. :-)
HTH
Giuseppe  

On Monday 28 October 2013 21:12:22 Halima Zaari wrote:
> dear Quantum espresso users
> i tried to compute GaN supercell with 56 atoms (attached file the dos and
> scf.out)
> the total dos of GaN has a mettalic behavior.if can someone to tell me is
> this correct and logic??
> thanks in advance


********************************************************
- Article premier - Les hommes naissent et demeurent
libres et ègaux en droits. Les distinctions sociales
ne peuvent être fondèes que sur l'utilitè commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et 
imprescriptibles de l'homme. Ces droits sont la libertè,
la propriètè, la sùretè et la rèsistance à l'oppression.
********************************************************

   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM)          
   Tel + 39 06 90672836 - Fax +39 06 90672316    
   E-mail: <giuseppe.mattioli at ism.cnr.it>
   ResearcherID: F-6308-2012