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Re: [lammps-users] Region instead of group
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Re: [lammps-users] Region instead of group


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Sun, 6 May 2018 10:19:58 -0400

On Sun, May 6, 2018 at 6:26 AM, Zohreh Ahadi <zohreh.ahadi@...24...> wrote:
> Dear all lammps user
>
> Thanks with your regarding , I have one question about the regions, It maybe
> considered easy but stop my project.
> I simulated the nanotube which filled water, the two end of nanotube are
> considered cold groups and the center of nanotube is hot group by NVT at
> specific temperature.
> I tested two strategy: Firstly , I considered the two end of nanotube with
> water, as cold group , after running  the  temp  result didn't match with
> the NVT temp which I set, and the cold group were very colder, and hot, was
> very hotter than I am set in NVT.
> Secondly:  I considered the two end of nanotube, without water as one
> group...again the result temp was not match.( The nanotube has low thermal
> conductivity)

actually, nanotubes have high thermal conductivity due to their
rigidity, but along the axis.

>
> Question:I would like to Know, Is it possible instead of one group, (cold or
> hot) the region set as NVT?( untill water moleculars when come or exit from
> this region feel the NVT)
>
> I am eager to know your advise for solving this problem.

your description is too vague to give specific advice. it looks from
your description, that you are not considering time scales (and
possibly also length scales) well enough and that you are looking at a
slow process. if that is the case, there is no use to accelerating
this process with a thermostat. you will replace computer simulation
with computer animation and the scientific value of your results will
approach zero.

axel.

>
> sincerely yours,
> Zohreh
> PhD student nano physics
>
>
>
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-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.