I am studying adatom diffusion barriers using NEB in LAMMPS. For surface barriers such as hopping and exchange, I can find similar results with other calculations in literature. However, the energy barriers for steps and kink sites are much smaller than expected results.
I have followed the documentation and the exact script for the example of NEB. I have tried to use both quickmin and fire minimizer and also i have tested different spring constants. I have selected all atoms in my simulations for "fix neb" command (ex: fix 1 all neb 1.0). There are not any other constraints in the system. However, in the movie of diffusion process, the migration of adatoms occur perfectly but all atoms in the system never minimize even the material is a nanostructure. Therefore, I think that the problem in my system is caused by the minimization procedure in NEB. I have worked with different metals (such as Cu, Ag …) using both eam and meam potentials but the same problem exists.
How can I correct the minimization procedure for all atoms in every image of NEB?