[Wien] Problem in optimization

[GOUTAM KUMAR GUPTA]

Dear all

Kindly give your feedback on optimization. I am facing a lot of problem of
QTLB-error. also as suggested change energy parameter value to take care of
this error. but the problem is if we change energy parameter then
comparison of final energy in the scf with different volume or c/a ratio
become difficult.

kindly suggest any reference on optimization of tetragonal structures for
both volume and c/a ratio with relaxed atomic positions.


Thanks

On Fri, Feb 24, 2017 at 11:04 AM, GOUTAM KUMAR GUPTA <pg201381002 at iitj.ac.in
> wrote:

> Dear all
>
> I am trying to optimize tetragonal Cu2ZnSnS4 lattice structure (lattice
> constant and c/a ratio both). What i did is
>
> 1) first i perform volume optimization at -4, -2,0,2,4 with simultaneous
> optimization of lattice positions using
>
> min -I -j "run_lapw -I -fc 1.0 -i 40 "
>
> in optimize.job script
>
> my volume optimization run fine and i get minima at 4 % change.
>
> 2) then for each volume i performed c/a ratio optimization at -4,-2,0,2,4
> using same command
>
> min -I -j "run_lapw -I -fc 1.0 -i 40 " in optimize.job file
>
>  Now during my c/a ratio optimization i got minima for 0%, 2% and 4%
> volume case. but for -4% and -2% volume change i do not get minima and the
> c/a ratio optimization curve do not show single minima. hence i am facing
> problem in finding optimized lattice parameters with optimized lattice
> position. as i an unable to get lowest energy structure.
>
> 2) Some times i see that for 0, 2, 4% volume change optimization runs well
> but for lower volume change say 1% or 3% it shows QTLB error (keeping all
> other parameters same). I do not know the exact reason for this.
>
>
> Kindly give your feedback. If i am doing any wrong in optimization script
> the kindly suggest modified optimization script for both volume and c/a
> ratio optimization.
>
>
> Thanks
> --
> *Goutam Kumar Gupta*
> *Mob:8561995547*
>



-- 
*Goutam Kumar Gupta*
*Mob:8561995547*
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