[gmx-users] pressure coupling for self-assembly of bilayer

[LeeHwan-kyu]

Dear GMX-users,

I'm trying to do self-assembly of bilayer. I'm using coarse-grained model (MARTINI), and there are 1280 CG lipids and 30110 CG waters. I followed procedures of Marrink and de Vries's atomistic simulations of the bilayer self-assembly.  So, I simulated the randomly-positioned system with isotropic pressures for a while, and then run the system with anisotropic pressure (shown below).  I've tried this a couple of times, but I always got tilted multiple bilayers (due to anisotropic pressure, the box x,y,z dimensions become even awkward.).   How can I get only one bilayer (normal to z-direction) ?   Do I need to apply other pressure couplings?  Or, am I using too much water?
 
Thanks for your help in advance.

best,
Hwankyu.

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tau_p                = 0.2   0.2   0.2   0.2   0.2   0.2
compressibility   = 3e-5 3e-5 3e-5 3e-5 3e-5 3e-5 
ref_p                = 1.0   1.0   1.0   1.0   1.0   1.0
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