[Pw_forum] VC_relax

[Ari P Seitsonen]

Dear Vishal Gupta,

   Your cut-off energy looks _very_ low, no matter which elements/pseudo 
potentials you do employ. Probably your system becomes metallic upon the 
relaxation, so I would include some kind of broadening of the occupation 
numbers, in addition possibly using the mixing mode 'local-TF', if you 
have vacuum in your system.

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 31 Mar 2016, Vishal Gupta 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 0.108. After some time. the force started increasing and now the
> iterations don't converge even in 400 steps. The input file is
>  /
>  &SYSTEM
>                        ibrav = 0,
>                          nat = 40,
>                         ntyp = 1,
>                      ecutwfc = 12 ,
>  /
>  &ELECTRONS
>                  mixing_beta = 0.3 ,
>              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
> 
> 
> 
> [487a748cedfb942f92401d52262f336d11784524388949.png]
> 
>