[lammps-users] fix_deform


When I use fix_deform to shrink a simulation box down to a desired density I’m getting the pressure of the system to be negative. The density I’m trying access has been simulated by others in the literature, and the simulation box contains a simple bead-spring polymer. The monomers interact via a repulsive LJ potential, so the pressure shouldn’t be negative. Does anyone have any suggestions?

Thank you for your time,


In the current version, compute pressure lets you list additional
args to extract components of the pressure. So if you define
extra compute pressures (in addition to the one thermo uses),
you could print each component with thermo_style custom.

I don't think there's anything preventing the bond contribution
to pressure from being negative.