[Wien] help :relaxation structure

[Laurence Marks]

Several points:

1) The *WARNING* is exactly that. You need to look at :FCHECK. Because your
structure does not have inversion symmetry the origin if not fixed. The sum
of the forces (:FCHECK) should be small; the current threshold for the
warning is too small in my opionion. If they are 1E-3 or less at the end
everything is OK; if they are 1mRyd/au or more then something is wrong.

2)  -ec 0.000001 is pretty meaningless;

3) Without either -min or use of mini/PORT you are not relaxing forces,
just printing them.

4) It is not impossible that the La 4f are an issue. However, it is not
clear that you in fact have a problem.

On Tue, May 29, 2018 at 11:33 PM, BUSHRA SABIR <b_sabir437 at yahoo.com> wrote:

> Hello wien2k users,
>
> I am working on complex metallic structure(30 atoms), while relaxing
> structure in scf, i use forces to relax with
>
> runsp_lapw -ec 0.000001 -cc 0.0001 -fc 0.1 -i 40 -p at 12*12*1 k mesh,
> after 150+ cycles graping warning command i receive following error(grep
> -e WARNING *.scf )
>
>
>
>
>
>
>
>
>
>
>
> *:ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.85370793 :WARNING
> Sum of forces not small, possible numerical issues :ENE  : *WARNING** TOTAL
> ENERGY IN Ry =      -124754.85322264 :WARNING Sum of forces not small,
> possible numerical issues :ENE  : *WARNING** TOTAL ENERGY IN Ry =
> -124754.85242433 :WARNING Sum of forces not small, possible numerical
> issues :ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.85211077
> :WARNING Sum of forces not small, possible numerical issues :ENE  :
> *WARNING** TOTAL ENERGY IN Ry =      -124754.85215409 :ENE  : *WARNING**
> TOTAL ENERGY IN Ry =      -124754.85217834 :ENE  : *WARNING** TOTAL ENERGY
> IN Ry =      -124754.85220196 *
>
> *:ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.85222572 *
> i go through mailing list and reduce k mesh to 5*5*1 for crude calculation
> and change convergence parameter
> runsp_lapw -ec 0.000001 -cc 0.0001 -fc 10 -i 40 -p
> make changes in Rmt values as following
> La 2.5 to 2.00
> Ru 1.9 to 1.95
> Al 1.74 to 1.72
> O  1.64 to 1.68
> although it reduce convergence time(30 min to 4 min) but i am still facing
> this warning after 80 cycles(grep -e WARNING *.scf )
>
>
>
>
>
>
>
>
>
>
> *:ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.72136831 :WARNING
> Sum of forces not small, possible numerical issues :ENE  : *WARNING** TOTAL
> ENERGY IN Ry =      -124754.71973897 :WARNING Sum of forces not small,
> possible numerical issues :ENE  : *WARNING** TOTAL ENERGY IN Ry =
> -124754.72290931 :WARNING Sum of forces not small, possible numerical
> issues :ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.72038403
> :WARNING Sum of forces not small, possible numerical issues :ENE  :
> *WARNING** TOTAL ENERGY IN Ry =      -124754.71984350 :WARNING Sum of
> forces not small, possible numerical issues *
> *:ENE  : *WARNING** TOTAL ENERGY IN Ry =      -124754.72018624*
>
> Kindly need help to deal with this problem
>
> Bushra Sabir
> PhD scholar,
> Pakistan
>
> ------------------------------
>



-- 
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A
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