[Pw_forum] Fw: Contracting cell volume for supercell in vc-relax

Ari P Seitsonen Ari.P.Seitsonen at iki.fi
Sun Oct 29 20:37:25 CET 2017

Dear Amar,

   A general comment: Have you considered why your cell changes so much 
from the initial one? It is hard to say without seeing the input. If you 
think that the job is meaningful, you could take the latest cell vectors 
and atomic positions and start with 'from_scratch' again. But usually when 
I have had this messsage, I have ended up realising that my initial 
structure was somehow errorneous.

     Greetings from Paris,


   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 Sat, 28 Oct 2017, Amar Singh wrote:

> Hi Friends,
> ​I am trying to optimize a supercell using vc-relax using ibrav = 14, unit cell volume keeps on shrinking and finally ends up with an error "Not
> enough space allocated for radial FFT: try restarting with a larger cell_factor". Using cell factor = 8 and ecutrho = 10 X ecutwfc helped a bit
> in reducing the rate at which volume of cell decreases / SCF cycle, but not solved the problem completely. Can these variables be increased
> further ?
> Would be thankful for any suggestion on it.
> Thanks
> ​Amar
> ​MGRU, Chennai

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