[CP2K:5116] Re: Equipartition and calculation of vibrational, rotational and translational Temperatures

[Rasoul Nasiri]

I need to estimate temperature of the non-equlibrium system using kinetic
energy
which can obtained by generalized equipartition.

Is there any other way so that I can measure it?





On Thu, Mar 27, 2014 at 7:24 PM, Carlos Campana <campa... at gmail.com>wrote:

> Why would you expect equipartition to hold in a non-equilibrium system? If
> one cannot define the partition function, how are quantity averages to be
> computed? Might be different when the non-equilibrium system achieves a
> certain steady-state...
> These are my 2 cents (haven't dusted my stat mech in a long time...)
> Carlos
>
>
> On Thu, Mar 27, 2014 at 3:06 PM, Rasoul Nasiri <nasir... at gmail.com>wrote:
>
>> Hello Matt,
>>
>> Many thanks.
>>
>> I think even using NVE, one will be dealt with some errors in
>> non-equilibrium situations. Could anybody please comment on it?
>>
>> Probably the reason is related to <mv2> = KBT in vibrational modes.
>>
>> Best,
>> Rasoul
>>
>>
>> On Thu, Mar 27, 2014 at 7:23 PM, Matt W <MattWa... at gmail.com> wrote:
>>
>>> Hi, interesting question, and I'd hope of interest to a few.
>>>
>>> I can't give a proper answer, but I think, in general, if you are not in
>>> equilibrium, equipartition is going to break - waving hands:
>>>
>>> (i) you can't define your modes properly.
>>> (ii) Also, most (all?, maybe some Langevin types recently implemented
>>> might escape this) thermostats only work at equilibrium too, so you'd be
>>> running NVE or similar where temperature isn't defined properly for a small
>>> cluster.
>>>
>>> I guess there are tricks for steady-state thermostatted non-equilibrium
>>> processes, but that is well beyond anything I know about.
>>>
>>> Matt
>>>
>>>
>>> On Thursday, March 27, 2014 10:16:07 AM UTC, Rasoul wrote:
>>>>
>>>> Dear All,
>>>>
>>>> Apologize if my question seems to be irrelevant for CP2K users.
>>>>
>>>> I'm trying to do a non-equilibrium MD simulation using CP2K in which
>>>> one molecule attacking the nano-droplet.
>>>>
>>>> My question is whether the equipartition of kinetic energy is satisfied
>>>> in the code for vibrational, rotational and translational modes at high
>>>> temperatures and non-equilibrium situations?
>>>> Having said this if <mv2> = KBT works properly for estimation of
>>>> temperature in the vibrational modes even using small time steps?
>>>>
>>>> Many thanks,
>>>>
>>>> Best,
>>>> Rasoul
>>>>
>>>>
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