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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

I guess that you have checked convergence of your result with respect
to kpt and ecut ?
Also have you checked that you are performing your calculation at the
equilibrium lattice parameter ? Your input cell parameter seems small
and may explain part of the discrepancy between your result and
litterature.

regards

PMA

On Tue, Sep 16, 2008 at 9:20 AM,  <mozhganamini@yahoo.com> wrote:
> Dear all,
> I'm trying to calculate the elastic constants of PbTiO3 for comparing the
> results with:  " Y. Liu et al. , Materials Science and Engineering A 
> 472(2008)
> "
> but my results are approximately twice the results in this article!?
> Thanks a lot in advance
>
> my results for elastic            results in article
> C11: 629 (GPa)                               383
> C12: 192                                         151
> C44: 116                                         120
>
> my input file:
>
>  acell  3*3.863 angstrom
>  rprim 1.0  0.0  0.0
>           0.0  1.0  0.0
>           0.0  0.0  1.0
> #Definition of the atom types and atoms
>  ntypat   3
>  znucl   82 8 22
>  natom   5
>  typat   1 3 2 2 2
>
>  xred  0.0    0.0    0.0
>        0.5    0.5    0.5
>        0.5    0.5    0.0
>        0.5    0.0    0.5
>        0.0    0.5    0.5
>
>  nband   13
>
> #Definition of the plane wave basis set
>   ecut   45.0
>  ecutsm   0.5
>
> #Definition of the k-point grid
>  kptopt   1
> ngkpt   6 6 6
> nshiftk   1
>  shiftk   0.5 0.5 0.5
>
> #Definition of the self-consistency procedure
>  diemac   6.0
>   iscf   5
>  nstep   100
>



-- 
Pierre-Matthieu Anglade