[gmx-users] keep the size of simulation box constant in one direction

[凌未风]

Hi there, 

I am simulating a membrane using charmm force field, unfortunately I always found huge fluctuation of the box size. I am wondering whether it is possible to fix the box size in the z direction, and allow pressure coupling in xy directions? How could we set up this in the mdp files?

Thanks a lot for your time and help. 

Sincerely yours, 
Ruoxu Gu