Added this to LD_CONFIG.

    /usr/lib64/mpi/gcc/openmpi4/lib64/libmpi.so.40

To compile/link/run

    /usr/lib64/mpi/gcc/openmpi4/bin/mpicc -h
    /usr/lib64/mpi/gcc/openmpi4/bin/mpicc --showme:compile
    /usr/lib64/mpi/gcc/openmpi4/bin/mpicc -g -c --showme:compile
    /usr/lib64/mpi/gcc/openmpi4/bin/mpicc -g -c hellompi.c 
    /usr/lib64/mpi/gcc/openmpi4/bin/mpirun --hostfile hosts -np 4 hellompi

    /usr/lib64/mpi/gcc/openmpi4/bin/mpirun --hostfile hosts -np 4 seer -s hellompi