[gmx-users] Skewed box using Parrinello-Rahman pressure coupling

[reich at mpikg.mpg.de]

Dear Gromacs-users,

I have been performing simulations with cubic and octahedron-shaped boxes
using Parrinello-Rahman pressure coupling. After some time I get the error
message "Could not correct too skewed box" and the simulations crash.
I set the parameters for the coupling as listed below:

pcoupltype               = isotropic
tau_p                    = 5.0
compressibility          = 5e-5
ref_p                    = 1.0


I have never encountered the same problems when using Berendsen pressure
coupling so I suppose I must have made a bad choice for some parameter for
the Parrinello-Rahman barostat. I tried to equilibrate my system using a
Berendsen barostat before switching to Parrinello-Rahman for 1ns (and
tau_p=1.0) but this didn´t help. Do you have any clue about where the
problem originates from?


Best

Luther