[gmx-users] Box gets big when using walls during NPT

[Ahmed Mohammed]

Hello GMX users,

The initial size of the simulation box is 8x8x8. I need to use walls during
NPT production, thus I set up this
ewald-geometry      = 3dc
nwall                      = 2
wall-atomtype         = opls_097 opls_097
wall-type                = 12-6
wall-r-linpot             = -1
wall-ewald-zfac       = 3

I run energy minimization and everything was fine where Epot= -8.60360e+06
and Fmax= 1.56230e+02. EM followed by NVT and everything was fine as well.
The problem is when I start NPT simulation the box gets very big where it
reaches 50 nm in each direction in the first 100 ps.

Any ideas or suggestions to pass this issue?

Thank you
 Ahmed