[CP2K-user] [CP2K:15016] Re: The temperature I get is different from what I set when do massive and global thermostat.

[汤羽]

Hello,
    Thanks for your reply. I will change my input files according to
your suggestion and read the paper carefully. Thanks a lot.

Travis <polla... at gmail.com> 于2021年3月27日周六 下午1:44写道：

> Hi,
>
> Yes, use the configuration from geometry optimization to start MD. Though
> in your original post, the thermostat coupling constant is much greater
> than the length of the trajectory you ran, whether massive or global - it's
> not doing anything here. The velocities are randomized and scaled to the
> target temperature by default as well so you should expect differences in
> the initial temperature fluctuations. After running for some time and
> reaching equilibrium, the average temperature from both thermostat settings
> should be equal. The massive thermostat controls every degree of freedom so
> it should get to the target temperature in fewer MD steps, making it ideal
> for equilibration. You should exercise caution in using MASSIVE for a given
> thermostat and coupling constant when you are interested in dynamic
> properties during data collection (aka production) runs. See, J. Chem.
> Theory Comput. 2013, 9, 2887−2899.
>
> -T
>
> On Friday, March 26, 2021 at 10:15:18 PM UTC-4 tang... at gmail.com
> wrote:
>
>> Hello Julian,
>>      Thanks for your suggestion. I will do geometry optimization
>> immediately. However, I'm a little confused about the last sentence  in
>> your reply, whether I should use the structure gotten by geometry
>> optimization to run massive and global thermostat firstly and than run
>> others processing? I hope i have expressed my question clearly.
>>       Tangyu.
>>
>> Julian Heske <j... at gmail.com> 于2021年3月26日周五 下午11:03写道：
>>
>>> Hello,
>>>
>>> in order to run a MD calculation at a specific tempertare, you have to
>>> equilibrate the system first to reach your target temperature. The time you
>>> need to equilibrate your system is dependent on your initial configuration.
>>> Since you are starting with a structure which has a very high potential
>>> energy (-157,5 vs. ~ -168 a. u. of the others, see out.txt), this energy
>>> remains as kinetic energy in the system and the thermostat will need a long
>>> time to remove the energy from the system. You can first do a geometry
>>> optimization ( CP2K_INPUT
>>> <https://manual.cp2k.org/trunk/CP2K_INPUT.html> / MOTION
>>> <https://manual.cp2k.org/trunk/CP2K_INPUT/MOTION.html> / GEO_OPT
>>> <https://manual.cp2k.org/trunk/CP2K_INPUT/MOTION/GEO_OPT.html> ), which
>>> leads to an optimized structure. Then start your MD run with your obtained
>>> structure as initial configuration. However, you should then still take a
>>> look at the temperature and not use the equilibration steps for your
>>> analysis.
>>>
>>> Kind regards,
>>> Julian
>>> tang... at gmail.com schrieb am Freitag, 26. März 2021 um 15:16:33
>>> UTC+1:
>>>
>>>> Dears cp2k's users,
>>>>       I'm doing a vibration analysis exercise.When I did massive and
>>>> global thermostat, the temperature I get is different from what I set.
>>>> Could you tell me what causes this error? I would appreciate you generous
>>>> help. The input and output file are listed as follow.
>>>>
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