[CP2K-user] [CP2K:15062] Gentle Heating

[Lenard Carroll]

I believe now too that 2 ps is too short, it's not that it's impossible to
achieve, I just don't think it is enough time for the system to produce
sensible results in the process.

On Thu, Apr 1, 2021 at 2:23 PM Marcella Iannuzzi <marci... at gmail.com>
wrote:

> Dear Lenard, dear Thomas,
>
> I am still of the idea that defining these as NVT or NVE simulations is
> misleading,
> since the generated configurations do not belong to any of these
> ensembles.
> Moreover, adding some kinetic energy stepwise and running 10/20 ps to
> equilibrate end explore, at least partially, the corresponding ensemble, is
> for sure much better than increasing the temperature from 0 to 800K in 2
> ps, as was the original intention.
> Best
> Marcella
>
>
> On Thursday, April 1, 2021 at 12:29:54 PM UTC+2 tkuehne wrote:
>
>> Dear Lenard,
>>
>> alternatively you may try using TEMEPRATURE_ANNEALING with values
>> slightly larger than 1.
>> However, this corresponds to an exponential not linear increase in
>> temperature.
>>
>> Cheers,
>> Thomas
>>
>> Am 29.03.2021 um 18:45 schrieb Lenard Carroll <len... at gmail.com>:
>>
>> 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 <ma... 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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