Here are some useful links related to the MCNPX code:

The Radiation Safety Information Computational Center at Oak Ridge national Laboratory.
The Nuclear Energy Agency (Agence pour l'energie nucleaire) a specialised agency within the Organisation for Economic Co-operation and Development (OECD), based in Paris, France.
X-Windows source code used for MCNPX graphics.
MCNP5.
The LAHET Code System Used as the basis for MCNPX high-energy physics.
The MCNP Visual Editor used for MCNP visualization
The Sabrina code for MCNPX and MCNP geometry visualization
The Moritz geometry editor and viewer for MCNPX and MCNP

Links for other High Energy Monte Carlo Codes:

Code Comparison Chart for All-Particle Monte Carlo Codes
The Fluka code at INFN
The GEANT4 code at CERN
The MARS code at Fermilab

Links for multiprocessing tools:

MPICH - A Portable Implementation of MPI at Argonne National Lab
PVM - Parallel Virtual Machine at Oak Ridge National Lab

Links for Linux compiler:

Generally Linux versions of MCNPX are compiled with the Intel compiler. If you are using the Linux Portland Group executables and don't have the Portland Group compiler, download and install their portability package, which is free and contains various missing .so files. You may need to know that our Linux executable was built with PGF90 4.0 on Red Hat 8.0.