[CP2K-user] [CP2K:10486] barostat problem NPT

Thomas Kühne tku... at gmail.com
Thu Feb 7 14:56:25 UTC 2019

Dear Simin, 

due to the fact that the fluctuations are proportional to the square root of the number of 
particles your pressure as a function of time seems to me very reasonable. I hence, 
would only suggest to substantially reduce the timecon to a much lower value, e.g. 
50 - 100fs. Also, please keep in mind that the region in the thermostat section is by 
default global, which to the best of my knowledge, only couples to 3 degrees of freedom 
of the whole system! So better use massive to equilibrate your system. 


> Am 06.07.2018 um 16:51 schrieb simin pahlavi <simin.... at gmail.com>:
> Dear Cp2k usrs,
> I am new in CP2K and I am trying to simulate 190 water molecule in T=800 k and P=4500 bar by the means of AIMD.
> I have a question about the barostat in CP2k. According the previous articles I have used CSVR barostat with timecon 2000 fs.
> As I have attached the plot of instantaneous pressure, the fluctuation in pressure are about -4500 to 4500.
> I have tried to change the timecon to the smaller value after 4000 fs relaxation to 1000 but the fluctuation did not change that much.
> I appreciate it if you recommend me a convenient barostat and thermostat for the system in hand.
> Thanks in advance 
> simin
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> <pressure.png><water.inp>

Prof. Dr. Thomas D. Kühne
Dynamics of Condensed Matter
Chair of Theoretical Chemistry
University of Paderborn
Warburger Str. 100
D-33098 Paderborn
tdku... at mail.upb.de

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