[gmx-users] Error when using mdrun_mpi

[Hanin Omar]

Hello all,I  am using gromacs 2019, i installed openmpi and did the buil mdrun only option, however when i type the command 
 mpirun -np 6 -v mdrun_mpi -multidir replica-[012345] -s 1a1z-md.tpr -x 1a1z-md.xtc  -o 1a1z-md.trr -c 1a1z-md.pdb -replex 500i get the following errormpirun was unable to find the specified executable file, and therefore
did not launch the job.  This error was first reported for process
rank 0; it may have occurred for other processes as well.

NOTE: A common cause for this error is misspelling a mpirun command
      line parameter option (remember that mpirun interprets the first
      unrecognized command line token as the executable).

Node:       tesla
Executable: mdrun_mpi
--------------------------------------------------------------------------
6 total processes failed to start

can someone tell me how to solve this issue? why is the openmpi wrapper doesnt recognize the mdrun_mpi command from gromacs?Hanin