[CP2K-user] [CP2K:15032] Gentle Heating

[Lenard Carroll]

But adding the kinetic energy all at once would result in the system acting
non-physically. I know this as I've done classical MD simulations for
years. I like the approach of multiple NVT simulations, gradually
increasing the temperature. I think I will also be using the previous
temperature's final trajectory/velocities for the new temperature NVT
simulation.

Thanks

On Mon, Mar 29, 2021 at 4:20 PM Marcella Iannuzzi <marci... at gmail.com>
wrote:

> Dear Lenard,
>
> Heating the system by constantly rescaling the velocity generates a
> dynamics that does not correspond to any meaningful thermodynamic ensemble.
> For sure, to set up a thermostat while forcing the temperature to change
> is not a good idea.
> If you want to use the ANNEALING in cp2k just set NVE, obviously the
> energy is not going to be conserved.
> Activating the annealing, at each step the actual temperature is
> multiplied by the scaling factor and the velocities are rescaled
> accordingly.
>
> Probably a better way to bring the system from a lower to a higher
> temperature would be to run a set of NVT simulations at increasing
> temperature, say 150K, 300K, ...800K
> Each simulation should be several ps long, such that the system has the
> time to sort of equilibrate at each temperature before ramping up.
>
> best
> Marcella
>
>
> On Monday, March 29, 2021 at 4:19:17 PM UTC+2 jos... at gmail.com wrote:
>
>> There is no way to do 800K over 2 ps.
>>
>> On Mon, Mar 29, 2021, 15:03 ASSIDUO Network <len... at gmail.com> wrote:
>>
>>> Good day, I trust you are doing well.
>>>
>>> I'm in the process of getting my hands dirty with AIMD using CP2K. I am
>>> familiar with MD simulations from AMBER, but not quite yet CP2K.
>>>
>>> I would like set up a gentle heating in my AIMD simulation, gently
>>> heating the box up from 0 K to 800 K. I have read on this group that
>>> annealing should be used for this, but my issues here are the following:
>>> - The heating phase has the volume and number of molecules constant, but
>>> allows the energy, the temperature and the pressure to change. None of the
>>> ensembles seem to fit this. So, I decided to go with NVT since that is what
>>> I have used with the heating simulation with AMBER (many tutorials
>>> available on it), but there you could specify the initial and reference
>>> temperature.
>>> - How do I properly use annealing to heat the temperature up from 0 K to
>>> 800 K over 2 ps? Annealing just scales the velocities of the particles, so
>>> I'm not sure how to best choose this scaling factor.
>>> - How do I print the temperature throughout the AIMD run?
>>>
>>> I have included my input file. I would appreciate if you could go
>>> through the &MOTION section and tell me if it all makes sense.
>>>
>>> Kind regards,
>>> Lenard
>>>
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