[lammps-users] How to set the pressure of NEB process

Dear LAMMPS users,

I’m trying to assess the effect of pressure on migration barriers. My goal is to compute migration barriers at various pressures. I tried to minimize my system prior to the NEB calculation using fix box/relax at a desired pressure. The system relaxed at that pressure but, during the NEB process, while the volume remained constant, the pressure deviated considerably from the desired value.

Is there a way to control the pressure during the NEB process so as to be sure that the barriers we get correspond to the defined pressure?



I don’t know how you are are monitoring the pressure during NEB. Each replica would
have its own pressure in its log file I suppose. But you should not be trying to run
NPT during NEB, just NVE, i.e. constant volume, as it is effectively a minimization process.
So I don’t think the pressure during NEB is relevant.

I suggest you equilibrate to a desired pressure before NEB, then switch to NVE and run NEB.
The barrier NEB gives will be the barrier at the desired pressure. I.e. for a system with atoms
slightly compressed or expanded.