[Pw_forum] VC_relax doesn't converge

[ashkan shekaari]

Dear Gupta,
Your ecutwfc is too small. Try with a larger value.

*--*
*All the best,*
*Ashkan Shekaari*
*Plasma Physics Research Center, **Science and Research Branch, *
*I A U, **14778-93855 Tehran, Iran.*
*0098 (933) 459 7122*

On Mon, Apr 18, 2016 at 9:47 PM, Vishal Gupta <vishal.gupta at iitrpr.ac.in>
wrote:

> Hi all,
> I've been running a vc_relax calculation on a 40 atom system. The
> calculation works fine for some cycles. The total force had come down to
> 0.06108. After some time. the force started increasing monotonically. Ive
> tried Gaussian broadening by using smearing=mv and tried degauss from 0.1
> to 4.0D0 but there isn't much change in the minimum of force. Also, I cant
> change K-points or Ecut as both of them are already at best values.
>  The input file is
>  /
>  &SYSTEM
>                        ibrav = 0,
>                          nat = 40,
>                         ntyp = 1,
>                      ecutwfc = 12 ,
>                   occupations ='smearing' ,
>                     smearing='mv'
>                     degauss = 0.05D0 ,
>
>  /
>  &ELECTRONS
>                  mixing_beta = 0.3 ,
>              mixing_mode='TF' ,
>              diagonalization = 'david' ,
>              electron_maxstep = 200 ,
>  /
>
> [&Ions/]
> /
> &CELL
> cell_dynamics= 'sd' ,
> cell_dofree='xy' ,
> /
>
> CELL_PARAMETERS angstrom
>     22.265358047804796    0.000000000000000    0.000000000000000
>      0.000000000000000   11.131216979724510    0.000000000000000
>      0.000000000000000    0.000000000000000   10.000000000000000
>
> P.S. Ive tried changing cell dynamics to 'damp-pr' , 'sd' and 'damp-w',
> but the same problem persists.
> Can anybody Please help me identifying the mistake ?
> Thank You.
> Best Regards,
> Vishal Gupta
>
> B.Tech. 3rd year Mechanical
> Indian Institute of Technology Ropar
> Rupnagar (140001), Punjab, India.
> Email :- vishal.gupta at iitrpr.ac.in
> RMML, IIT Ropar
> <https://sites.google.com/a/iitrpr.ac.in/ropar-mechanics-of-materials-laboratory/people>
>
>
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