Dear Axel

Thanks for the info about the command line output.

On the STUBS library it works ok for just one instance of lammps but say if
I want to run many serial instances of lammps. Is it possible to force
lammps to only use a processor id which is set in a parent function.

you have to provide more details about what you are doing and how you
detect, that things are not working the way you expect.

the easiest way to make certain that each LAMMPS instance uses a
specific processor is to use MPI in the top level software, the use
MPI_Comm_split() to generate subcommunicators (in the most extreme
case one for each MPI rank) and then pass those to the lammps_open()
function, provide the LAMMPS library was compiled using the *same* MPI
library (you cannot mix and match).