[CP2K:751] Re: using empirical VDW correction with CP2K

[Teodoro Laino]

Dear Limin,

Please read carefully the error/warning  messages:

On 10 Mar 2008, at 01:36, lmliu wrote:

> *** 01:34:59 WARNING in force_env_methods:mixed_energy_forces  
> err=-300   ***
>  *** ASSERTION (cond) failed at line   1151 Error (0.129985E-11)  
> in       ***
>  *** computing numerical derivatives larger then 
> (0.100000E-11) .          ***


First: this is not an error message but it is a warning (WARNING in  
[..]).
Second: It clearly says that: Error (0.129985E-11) in computing  
numerical derivatives larger then(0.100000E-11) .

I guess you can cope with this error on the evaluation of the MIXED  
forces.. don't you (look at the magnitude of the numbers)?
If you are annoyed from seeing this warning message you can tune the  
precision of the evaluation of the numerical derivative
with the keyword:

http://cp2k.berlios.de/input/ 
InputReference~__ROOT__~FORCE_EVAL~MIXED~GENERIC.html#ERROR_LIMIT

10^-12 is an extremely safe parameter. I guess 10^-7 will do your  
work in a very good way as well (please compare these numbers
with the precision achieved in computing the DFT forces).
Cheers,
Teo

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