[Pw_forum] QE & Xcrysden

[Sebastijan Peljhan]

Dear Cecil, 

On Wed, 2010-03-10 at 11:44 +0300, naphtaly moro wrote:
> Dear Q.E. & Xcrysden
> I am working on the various phase transitions of GaAs. I am trying to
> contact these structures. I ahve managed to construct the ZB and RS
> structures with success. I am using Xcrysden with Quantum Espresso.
> When i try to view the CsCl-GaAs structure,  I only see the Ga atoms
> and with no As atoms in the matrix. Can someone show me please where I
> am going wrong
>  my input file is this
>  &control
>    prefix='GaAs',
>    pseudo_dir='/home/physics/Desktop/espresso-4.0.5/pseudo'
>    outdir = './tmp',
>  /
>  &system

ibrav = 3 represents bcc cubic cell, hence the Ga and As atoms in your
structure overlap. Xcrysden actually warns you, that some of the atoms
overlap and they will be deleted. 

According to QE example06 you should try with ibrav = 2 (fcc) and As
atom at (0.25 0.25 0.25) position.  


Cheers,

Sebastijan


>    ibrav=  3, celldm(1) =10.2, nat=  2, ntyp= 2,
>    ecutwfc = 12.0,
>  /
>  &electrons
>  /
> ATOMIC_SPECIES
>  Ga  69.723  Ga.pbe-nsp-van.UPF
>  As  74.9216 As.pbe-n-van.UPF
> ATOMIC_POSITIONS
>  Ga 0.00 0.00 0.00
>  As 0.50 0.50 0.50
> K_POINTS {automatic}
>  4 4 4 0 0 0
> 
> Thanks
> 
> 

-- 
Sebastijan Peljhan
Department of Physical and Organic Chemistry
"Jozef Stefan" Institute
Jamova 39
1000 Ljubljana
Slovenia

tel.:+386 1 4773 523
fax.:+386 1 4773 822
email: sebastijan.peljhan at IJS.SI