[gmx-users] A question on comm_grps option

[Hwankyu Lee]

Dear, gmx-users,

I'm running a system that there are two monolayers which has a peptide 
for each like picture.

IIIIIIIIIIIIIIIIIIImonolayer
     (Pep)

    (water)

     (Pep)
IIIIIIIIIIIIIIIIIIImonolayer

Initially, I set up peptide in the middle of the monolayers, but when I 
ran this system first time, I could see that the peptides were moving 
to the edge of the monolayers.  I then used "comm_grps" option like 
"comm_grps = Lower_lipids Upper_lipids", which means I removed center 
of mass motion of two monolayers. After that, it was shown that 
peptides were kept in the middle of the monolayers stably.  I would 
like to make sure if it is right because I'm wondering I also need to 
remove center of mass motion of water.
Do I need to remove center of mass motion of water ?
Could you give me any advice?

best,
Hwankyu.