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Re: [lammps-users] Calculation density of water in nanotube
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Re: [lammps-users] Calculation density of water in nanotube

From: Axel Kohlmeyer <akohlmey@...24...>
Date: Mon, 6 Nov 2017 10:01:23 -0500

i'll add two more items to julien's list:
- what is the density change for a bulk water system of the same water potential? most classical water potentials are particularly bad at getting the experimental behavior around the melting point right.
- as an indirect measure consider the following: does the number of water molecules inside the nanotube change? does the diameter of the nanotube change?

and to emphasize his last point:
unless the nanotube has a sufficient diameter, you cannot automatically expect bulk-like behavior from whatever is in there. considering the popularity of nanotubes over the last 20+ years, there must be a wealth of publications on the subject. a proper and sufficiently deep study of the published literature is thus strongly recommended. don't expect that a post to a mailing list can serve as a sufficient replacement.


On Mon, Nov 6, 2017 at 9:45 AM, Julien Guénolé <julien.guenole@...4839...> wrote:
First of all, as you described you issues, they are not Lammps related
but rather physics/scientific problems. Your colleagues/supervisor are
better positionned to address them.

On 06/11/17 14:36, Zohreh Ahadi wrote:
> Dear all,
> I would like to calculate the  density of water in nanotubes when the
> temperature of them are changed, 
> in order to calculation of density I used the (mass of water)/volume
> inside of  Nanotube, but when the water convert to ice again I reach
> to the same density!!, 1_ how can I fix this problem?
Not enough information (type and succession of simulations, exact
procedure,...) to know from where you "problem" comes.
> 2_ how I can calculate only the volume of water group in nanotubes?
If it is "inside" the NT (e.g. no interface water/vacuum), using a
Voronoi approach might be relevant.
>  3_ is it possible I calculated the radial density of water in
> nanotubes which the center of Nanotube be the origin?
yes. But keep in mind that a density is a volume averaged quantity. So a
minimum volume has to be considered to make it consistent.
> Regards,

Dr. Julien GUÉNOLÉ
Postdoctoral researcher
Department of Materials Science & Engineering
Institute 1: General Material Properties
Friedrich-Alexander-University Erlangen-Nürnberg
Martensstr. 5, 91058 Erlangen, Germany
-----------------------  Office 3.40
Phone [office] (+49) 91 31 85 27 486
Email          julien.guenole@...4839...
Twitter        @nanouayeur

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Dr. Axel Kohlmeyer  akohlmey@...92......
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.