[Pw_forum] Problem in DOS results

[Gabriele Sclauzero]

Dear Padmaja,

   are you sure that your calculation has been converged wrt the k-point sampling? I believe that if you build the supercell correctly and change the k-point sampling accordingly you'll get the same DOS. In principle this should hold even if you didn't converge wrt the size of the k-point mesh, though not completely sure that this is true also for tetrahedra method occupations. 

Please post at least the atomic positions, lattice parameters and the content of the K_POINTS input card, otherwise it will be impossible to help you further...

GS

Il giorno 04/lug/2010, alle ore 21.56, Padmaja Patnaik ha scritto:

> Dear all
> 
> I am studying the properties of a compound semiconductor using super cell calculations. I have generated super cells by expanding the lattice constant 2times, 3 times and 4 times in all the directions. My calculations gives correct results for 2 times and 4 times extended super cells but not for 3 times extended onel. I have made sure that the generated atomic co-ordinates are correct. I have tried fixing all the required parameters like, k points, ecutwfc and nbnd. But still its not working. after doing the scf calculations I do the DOS with occupations=tetrahedra. But the DOS plot for the second case is found to be much different from expected while for all other cases the results match. What can be the probable mistake i am doing? Please suggest.
> 
> Padmaja Patnaik
> Research Scholar
> Dept of Physics
> IIT Bombay
> Mumbai, India
> 
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§ Gabriele Sclauzero, EPFL SB ITP CSEA
   PH H2 462, Station 3, CH-1015 Lausanne

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