I've been having difficulty in successfully compiling the MCNP executable with the MPI/MPICH libraries on Scientific Linux 6.x (whatever the latest version is). I'm currently using MCNP5, and the latest distribution DVD. The compiler is GCC, and the MPI is MPICH 1.4.x (the version immediately prior to MPICH 2). I've followed the LANL instructions precisely, and yet it won't generate the MCNP5.MPI executable that I need. If anyone could offer a suggestion for a combination of Linux OSand MPI that works relatively easily to generate the parallel MCNP5 that I want, I would greatly appreciate it. And perhaps some general code for successfully compiling MCNP with the MPI libraries on that particular OS. I can add some of the syntactical details of what I tried to do later, as they are all on another computer system. Thank you.