[Pw_forum] SCF Correction Too Large ...

[Stefano de Gironcoli]

Dear Victor M. Bermudez,

    tha code says that the force correction due to lack of self-consistencey is of comparable size to the total force you calculate so its precise value should not be trusted to that level...
you should further reduce the scf convergence threshold and the total scf correction should correspondingly decrease to a safer level.
however 10^-3 is already a quite small total force so not much should change in the results and this firther relaxation should be fast.

you could also check the use of the "upscale" variable for structural relaxation that should do this automatically.

  stefano


On 06/22/2012 12:59 AM, Vic Bermudez wrote:
> 	Here is my question. When I further reduce the threshold to 10^-8 I get
> essentially the same energy (-19483.4930127352 Ry) as for 10^-7, but I still
> get messages about the correction being too large. Upon convergence (at a
> 10^-8 SCF threshold) the message gives: Total force =     0.001688     Total
> SCF correction =     0.000449
> 	If I'm getting nearly-identical final energies for SCF thresholds of 10^-7
> and 10^-8, is there really still a problem at 10^-8 ?
> 	Thank you in advance for your help and advice.
>
> Best Wishes,
> Vic Bermudez
>
> Victor M. Bermudez
> Code 6876
> U.S. Naval Research Laboratory
> 4555 Overlook Ave., S.W.
> Washington, DC 20375-5347
>
>    Phone: 202-767-6728
>    FAX: 202-767-1165
>    E-mail: victor.bermudez at nrl.navy.mil
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum