Problem in NEB simulation to calculate vacancy diffusion barrier

Dears

I am trying to perform a NEB simulation with LAMMPS to calculate vacancy and interstitial diffusion barriers. I have followed the pattern provided in the example section (…/LAMMPS/examples/neb) and created my own input file. After running the input, following error appeared:

ERROR: Cannot use NEB with a single replica ( …/neb.cpp:139)

I read the LAMMPS documentation, which does not contain any helpful explanation to fix the problem. Being hopeless, I tried to run the original input file provided in LAMMPS directory in NEB section (in.neb.hop1 & final.hop1), but surprisingly, the error occurred persistently.
Can anyone help me with this problem? How can I create multiple replicas for my NEB simulation? and can anyone give me a brief description of what exactly LAMMPS does with NEB command? (I have read the correlated papers, but a brief explanation will be really helpful)

Dears

I am trying to perform a NEB simulation with LAMMPS to calculate vacancy and
interstitial diffusion barriers. I have followed the pattern provided in the
example section (.../LAMMPS/examples/neb) and created my own input file.
After running the input, following error appeared:

ERROR: Cannot use NEB with a single replica ( ../neb.cpp:139)

I read the LAMMPS documentation, which does not contain any helpful
explanation to fix the problem. Being hopeless, I tried to run the original

of course it does. you just have to wipe your screen and clean your
glasses. the very first line of the documentation says.

Perform a nudged elastic band (NEB) calculation using multiple
replicas of a system. Two or more replicas must be used; the first and
last are the end points of the transition path.

and then a little bit later it says:

Each replica runs on a partition of one or more processors. Processor
partitions are defined at run-time using the -partition command-line
switch; see Section_start 7 of the manual. Note that if you have MPI
installed, you can run a multi-replica simulation with more replicas
(partitions) than you have physical processors, e.g you can run a
10-replica simulation on just one or two processors. You will simply
not get the performance speed-up you would see with one or more
physical processors per replica. See _this section_ of the manual for
further discussion.

and the link to _this section_ points to:

http://lammps.sandia.gov/doc/Section_howto.html#howto_5

which explains how multi-replica calculations are launched.

if that is not helpful, then i don't know what else should be.

axel.