[Wien] [Warning message: Sum of forces not small, possible numerical issues]

Fri Apr 6 13:31:49 CEST 2018

To be efficient you should:

Start with an RKmax 0f 2.5 or 3.75 instead of 3 (check later)

Reduce k-points to 2x2x1 (check later).

run -it -p  -fc 10   # crude convergence before structure optimization !
                      # -p because you want to use the 16 cores. You 
have to define a suitable .machines file ! Are you sure you are using 
more than 1 core right now ???

Once this is converged, check forces (are they so big that you need to 
relax ? and :FCHECK. If :FCHECK is still large at the end, probalby your 
spheres are not ok. And in addition you should increase LVNS from 4 to 6 
in case.in1(c).

save, and only then start a run -p -it -min

On 04/06/2018 12:49 PM, Dr. K. C. Bhamu wrote:
>   Thank you Prof. Lyudmila for the inlined reply.
> 
> I shall mention the optimization process: I am using  run_lapw 
> ............ -it -min to relax the structure with TETRA (default), rmt 
> 3, kpt 50 (4x4x2), PBE. Organometallic system (Hybrideperovskite).
> 
> I am not sure whether my scf is going well or not because I do not see 
> any such message.
> My main concern is about too much time (~40 minutes on 16 core) for one 
> scf cycle and this warning.
> 
> 
> Could you please have a look at my further queries:
> 
> 
> 06.04.2018 10:09, Dr. K. C. Bhamu wrote:
> 
>         :WARN
>         :WARNING Sum of forces not small, possible numerical issues
> 
>     I'd look attentively around this place in the scf.
> 
> 
> 
> I do not find anything in scf with this statment or part of this 
> statment. Also, as per my excersie, nothing is mentioned in mailing list 
> for such warnings.
> 
> 
> 
>         below is constructive output from six scf cycles:
> 
>     All looks good, though I do not know what is :ADIST. Something
>     connected with MSR1a option.
> 
>         :ADIST   Largest Distance  1.71E+02 mau for atom  18
>         :ADIST   Largest Distance  1.67E+02 mau for atom  32
>         :ADIST   Largest Distance  1.20E+02 mau for atom  32
>         :ADIST   Largest Distance  5.87E+01 mau for atom  32
> 
> 
> :ADIST represents the distance between atoms (Pg number 212 UG). Atom 18 
> and 32 are H.  in the 12th Cycle :FGL is positive for both and is around 
> ~40mRyd/au.
> 
> 
>     Too large forces appear and movement of the atoms becomes too large.
> 
>                  TOTAL FORCE WITH RESPECT TO THE GLOBAL COORDINATE SYSTEM:
>         :FGL018:  18.ATOM              -228.797027515  -110.869626478
> 
> 
>     I think that mixer is very clever program, so this possibility is
>     taken into account, and it wiil correctly treat this data.
> 
> 
> results from :FGL and hence from :FCHECK is varying. In first cycle the 
> total forces from :FCHECK was very small and in the 8th Cycle total 
> forces are too high. The average totla force on each atom is
> 
> 
> results from FCHECk and FR are below (in 12th scf cycle):              
> FCHECK *.scf
>  > :FCHECK:   Sum of forces        -69.940627520    74.707201466   
> 256.655266254
>  > :FCHECK:   Sum of forces        -64.560329574    73.360823345   
> 231.480485436
>  > :FCHECK:   Sum of forces        -48.034175166    65.104093472   
> 166.986223927
>  > :FCHECK:   Sum of forces        -35.064695164    59.878383059   
> 106.378782186
>  > :FCHECK:   Sum of forces          1.658948381    44.163592598   
> -28.823131541
>  > :FCHECK:   Sum of forces         -1.715900623    54.670180112   
> -38.208248369
>  > :FCHECK:   Sum of forces        -44.599628242    84.665399276   
>   80.309287437
>  > :FCHECK:   Sum of forces       -104.389046420   114.231138278   
> 298.688183293
>  > :FCHECK:   Sum of forces       -146.872184802   138.002715039   
> 506.089724144
>  > :FCHECK:   Sum of forces       -139.929513824   116.740866115   
> 514.542253158
>  > :FCHECK:   Sum of forces        -44.458957001    53.512685999   
>   90.795768329
>  > :FCHECK:   Sum of forces        -21.346540908    53.389897235 
>   -190.728160314
> 
> 
> :FR *.scf
> 
>  > :FRMSA: (mRyd/au) 684.75( 18)  482.59 RMS (au) 2.11E-03 MAX 3.34E-03 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au) 666.97( 18)  473.06 RMS (au) 6.32E-03 MAX 1.00E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au) 620.05( 18)  446.96 RMS (au) 7.70E-03 MAX 1.22E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au) 564.83( 18)  415.40 RMS (au) 2.26E-02 MAX 3.60E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au) 410.77( 18)  314.76 RMS (au) 3.10E-02 MAX 5.00E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au) 228.80( 18)  169.19 RMS (au) 3.10E-02 MAX 5.00E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  65.91( 17)   47.66 RMS (au) 1.16E-02 MAX 2.21E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  57.84(  9)   41.34 RMS (au) 9.47E-03 MAX 1.98E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  76.92( 35)   55.05 RMS (au) 7.92E-03 MAX 2.08E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  68.91( 21)   60.53 RMS (au) 8.58E-03 MAX 1.53E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  59.32( 25)   53.55 RMS (au) 7.45E-03 MAX 1.32E-02 
> :F-cond.(mRyd/au)    2.00 F
>  > :FRMSA: (mRyd/au)  64.13( 13)   54.92 RMS (au) 6.46E-03 MAX 1.04E-02 
> :F-cond.(mRyd/au)    2.00 F
> 
> 
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-- 

                                       P.Blaha
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