[CP2K:4045] Re: Energy conservation NVT/NVE simulation

[paolo nicolini]

Hi,

I tried some test to assess the suggestions from Jorg and Matt. It follows 
the results. 
First the Matt's suggestions (all_matt_50ps.png):
- only decreasing the time step to 2.0 fs don't change the effect (red 
lines in NVT and NVE runs);
- putting the SHAKE_TOLERANCE key allows to get better results in the NVT 
runs but in the NVE ones it is appreciable a drift (blue and green lines).
However, the outcome is that the results with time step 2.0 and 2.5 are 
quite indistinguishable.

Regard to Jorg's suggestions (all_jorg_50ps.png):
- only changing the ewald parameter we get a drift even larger (red lines);
- by combining ewald changes with an enlarged shake tolerance I get the 
correct behaviour (blue lines).

To confirm it, I performed also a run with flexible molecules (all_flexible_50ps_cut.png) 
and I got almost flat profiles.

I tried also to change the real space cutoff value (that is not the same of 
the LJ interactions) but I got identical results as the one that I showed.

Best 
Paolo



Il giorno martedì 25 settembre 2012 11:45:03 UTC+2, paolo nicolini ha 
scritto:
>
> Hi
>
> thank you for the quick answers! I will try to follow your suggestions...
>
> My version is:
>
>  CP2K| version string:                    CP2K version 2.4 (Development 
> Version)
>  CP2K| source code revision number:                                        
> 12363
>  CP2K| is freely available from                             
> http://www.cp2k.org/
>  CP2K| Program compiled at                         Fri Sep  7 12:38:53 
> CEST 2012
>  CP2K| Program compiled on                                              
> titania1
>  CP2K| Program compiled for                                     
> Linux-i686-intel
>
> Best
> Paolo
>
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