[gmx-users] Water droplet in vacuum

David van der Spoel spoel at xray.bmc.uu.se
Thu Dec 31 20:56:10 CET 2015

On 31/12/15 20:38, Ray Chao wrote:
> ​Dear All,
> I am really new to MD simulation and Gromacs. I am now trying to simulate a
> simple case that a water droplet in the vacuum.  I was simulating a water
> sphere with diameter of 7.0nm and 6000 mols in it under NVT (initial water
> droplet was created on packmol). The water model is SPCE under gromos53a6.
> The water droplet should keep spherical in the vacuum. However in my
> simulation, a number of water mols dispersed into the vacuum. Since I am
> really new in this area, can anybody help me with this problem?
This is not a problem, this is normal. See e.g.

Carl Caleman and David van der Spoel: Temperature and Structural Changes 
in Water Clusters due to Evaporation in Vacuum J. Chem. Phys. 125 pp. 
154508 (2006)


> The google drive link tomy .mdp, .top and .gro files is also attached.
> Thank you very much.
> https://drive.google.com/open?id=0B3QHg0jyPMMYQWRabi02VzUxbFE
> https://drive.google.com/open?id=0B3QHg0jyPMMYaGpmbG42ckxGRkk
> https://drive.google.com/open?id=0B3QHg0jyPMMYOTF0NUMtSVpXUjA

David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se

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