[CP2K:1749] Re: different regions with different temperature in MD

[Jun Cheng]

Many thanks for the helpful suggestions.

Cheers,
Jun



On Mon, Feb 2, 2009 at 3:37 PM, Teodoro Laino <teodor... at gmail.com>wrote:

>
> Hi Jun
>
> then you don't need at all the different thermostatting region at
> different temperatures.
> You can specify velocities in the section &VELOCITIES in &SUBSYS.
> These velocities act like restart quantities.
>
> You can (with a small external program) determine the velocities of the
> hotter atoms through a Boltzman distribution at temperature T1, and the
> velocities of the other atoms at temperature T2 (T1>T2).
> You can then input these quantities in the &VELOCITIES section and run
> your MD.
>
> Of course you may consider about running an NVE ensemble instead of the
> NVT (which you were mentioning in your previous message). NVE  makes
> more sense to me in order to inspect heat transfer (but of course more
> expert people can comment on this point).
> Cheers
> Teo
>
> Jun Cheng wrote:
> > Thanks a lot for rapid reply, Teo.
> >
> > What I am trying to simulate is that a few atoms or molecules in an
> > equilibrated system are excited to higher vibrational levels (e.g. due
> > to photo adsorption), and see how the system evolves afterwards. I am
> > thinking of assigning the excited species an high temperature
> > initially to mimic the situation of excitation by photo adsorption,
> > and then seeing how the system reacts. So, it is not necessary to keep
> > the excited species at the high temperature during MD simulations.
> > Please let me know what do you think. Thanks.
> >
> > Jun
> >
> >
> >
> > On Mon, Feb 2, 2009 at 3:09 PM, Teodoro Laino <teodor... at gmail.com
> > <mailto:teodor... at gmail.com>> wrote:
> >
> >
> >     Dear Jun,
> >     it is possible to define different thermostatting regions but all of
> >     them have the same temperature.
> >     It would not work (most of the time) having different regions at
> >     different temperatures unless the regions
> >     are not fully adiabatic. In fact, different regions at different
> >     temperatures ( in case of energy flow between
> >     the different regions) would never thermalize to the temperature you
> >     asked for..
> >
> >     Cheers
> >     Teo
> >
> >     Jun wrote:
> >     > Dear all,
> >     >
> >     > Is it possible to define different regions with different
> >     temperatures
> >     > in a MD simulation using cp2k? If yes, how to do that?
> >     > Many thanks in advance.
> >     >
> >     > Jun
> >     > >
> >     >
> >
> >
> >
> >
> >
> > >
>
>
> >
>
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