[gmx-users] modeling evaporation NVP NVE

[pbuscemi at q.com]

Dear Users,

 

I am trying to understand a model of water evaporation and am asking for a
few of suggestions or just point to a link. 

 

So far I have modeled 10000 molecules of spce water and equilibrated to a
density near 1 gm/cc.   I then double the size of the box and then using 

p-couple Perinnelo-Rahmen,

Pcouple type         = surface-tension   or semiisotropic,

compressibility = 4.5e-5      4.5e-5 ,

ref P                      =1    0   

ref  temp  300 or 400K  and run for 0.5 ns 

 

What occurs is a few molecules from the cube form ( apparently ) a gas
phase. What I expected was the water to expand to fill the enlarged box.  My
run time may be too short so I'll run longer times  later.

But are my expectations incorrect - should not all the water expand ?    I
used an mpd type  NPT - should I use NVE  and if so how does that differ
from NPT other than setting tcoupl = no and pcoupl = no.   I can - and will
-  try this but it may be an incorrect approach as well

 

Paul