Intel® MPI Library User's Guide for Linux* OS
If you use one of these job schedulers, with the $PBS_ENVIRONMENT exists and the value is PBS_BATCH or PBS_INTERACTIVE , mpirun uses $PBS_NODEFILE as a machine file for mpirun. You do not need to specify the –machinefile option directly.
Example of a batch job script:
#PBS –l nodes=4:ppn=4
#PBS –q queue_name
cd $PBS_O_WORKDIR
mpirun –n 16 ./myprog.exe