[Pw_forum] problem with supercell

[Lorenzo Paulatto]

On 11/03/2013 07:18 PM, Halima Zaari wrote:
> dear quantum espresso users
> i tried to do input of GaN supercell with 56 atom
> I plots the dos of GaN it gives me mttalic behavior while in the
> literature is semiconductor.

Dear Halima,
in your input you write:
 ibrav=4,celldm(1)=12.06,celldm(3)=1,24,nat=56, ntyp=2,

note that 1,24 is different from 1.24 : it will make your cell too small
which can cause a system to become metallic.

I also noted that your value of ecutrho may be too low, as it is only
4*ecutwfc and you are usng ultrasoft (note van=Vanderbilt) pseudopotentials.

Finally, I do not understand what you're doing with the magnetization
and Hubbard U, but I'm don't know that method very well, hence I'll
leave any comment to more expert people.

good work!


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone:+33 (0)1 44275 084 / skype: paulatz
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