If you have a number of serial jobs to run you can run them simultaneously on one node. Each compute node has 12 cores so can run up to 12 copies of a serial program, provided there is enough memory (each compute node has 24GB RAM). For example this script file runs four serial programs:

#!/bin/tcsh
#PBS -l nodes=1
#PBS -l walltime=12:00:00

myprog1 &
myprog2 &
myprog3 &
myprog4 &

# wait for all the background jobs to finish. 
wait

See /usr/local/examples/qsub_script/example-serial.pbs for an example of how to run multiple serial jobs in different directories.

-- JohnRowe - 11 Jan 2008