So you mean that the command I am using “mpiexec” is from a different library but not the one in their system? They said if they commented out my “processors 2 3 2”, then it could be run under “mpiexec”. But when I saw the output file, there are still 12 of LAMMPS(10 Aug 2015). So I think your explanation makes sense. Do you know how to fix this problem?
Best wishes,
Andy
So you mean that the command I am using “mpiexec” is from a different
library but not the one in their system? They said if they commented out my
“processors 2 3 2”, then it could be run under “mpiexec”. But when I saw
the output file, there are still 12 of LAMMPS(10 Aug 2015). So I think your
explanation makes sense. Do you know how to fix this problem?
well, LAMMPS needs to be compiled and run with a consistent MPI
configuration on a properly installed machine. 
beyond that i would need a crystal ball and know/see what exactly is
happening during compiling and running.
this is one of the "if you do it right, it will work" things...
axel.