Run these examples as: mpirun -np 4 lmp_g++ -partition 4x1 -in in.neb.hop1 mpirun -np 4 lmp_g++ -partition 4x1 -in in.neb.hop2 mpirun -np 4 lmp_g++ -partition 4x1 -in in.neb.hop1.end mpirun -np 3 lmp_g++ -partition 3x1 -in in.neb.sivac mpirun -np 8 lmp_g++ -partition 4x2 -in in.neb.hop1 mpirun -np 8 lmp_g++ -partition 4x2 -in in.neb.hop2 mpirun -np 8 lmp_g++ -partition 4x2 -in in.neb.hop1.end mpirun -np 8 lmp_g++ -partition 4x2 -in in.neb.sivac Note that more than 4 replicas should be used for a precise estimate of the activation energy corresponding to a transition. If you uncomment the dump command lines in the input scripts, you can create dump files to do visualization from via Python tools: (see lammps/tools/README and lammps/tools/python/README for more info on these Python scripts) python ~/lammps/tools/python/neb_combine.py -o dump.hop1.combine -b dump.nonneb.1 -r dump.neb.* python ~/lammps/tools/python/neb_final.py -o dump.hop1.final -b dump.nonneb.1 -r dump.neb.* produces: dump.hop1.combine = series of snapshots for all replicas together time = progression of NEB calculation dump.hop1.final = series of snapshots for final state of all replicas time = replica #