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

[Lyudmila Dobysheva]

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.

> :WARN : QTL-B value eq.   2.79 in Band of energy  -0.76594  ATOM=    7  
this is not much, and can easily disappear at the following cycles. Only 
if it become more than 5 at final iterations of the scf cycle I would worry,

> :WARN : You should change the E-parameter for this atom and L-value in 
> case.in1 (or try the -in1new
Only in the above mentioned case.

> :ENE  : *WARNING** TOTAL ENERGY IN Ry =      -141317.23075973
This is a consequence of the former warnings, no other importance.

> ... :DIS  :  CHARGE DISTANCE       (  0.238821 for atom   15 spin 1)       
> 0.107937
:DIS's look good.

> 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

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.

So, the program warns you to look after the movement of the atoms with 
attention to atom 18 and 32.

Best wishes
Lyudmila Dobysheva
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Udmurt Federal Research Center, Ural Br. of Rus.Ac.Sci.
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