Running multiple serial jobs on clusters

This script describes a way to run multiple serial jobs on clusters.

#PBS -N serial.analysis
#PBS -j oe
#PBS -l walltime=4:00:00,nodes=22:ppn=16,gres=widow2

cd $PBS_O_WORKDIR
date
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PBS_O_WORKDIR

sort $PBS_NODEFILE | uniq > ./TEMP.NODEFILE

n=`wc -l ./TEMP.NODEFILE |awk '{print $1}'`
for((i=1;i<=$n;i++)); do j=`expr $i - 1`; sed -n ''$i','$i'p' ./TEMP.NODEFILE > host.$j; done

$MPI -np 1 --hostfile host.0 $NAMD ./w1_md3_resid_100.namd > ./w1_md3_resid_100.namd.out &
$MPI -np 1 --hostfile host.0 $NAMD ./w1_md3_resid_101.namd > ./w1_md3_resid_101.namd.out &
....
$MPI -np 1 --hostfile host.0 $NAMD ./w1_md3_resid_174.namd > ./w1_md3_resid_174.namd.out &
$MPI -np 1 --hostfile host.1 $NAMD ./w1_md3_resid_175.namd > ./w1_md3_resid_175.namd.out &
....
$MPI -np 1 --hostfile host.1 $NAMD ./w1_md3_resid_246.namd > ./w1_md3_resid_246.namd.out &
$MPI -np 1 --hostfile host.2 $NAMD ./w1_md3_resid_247.namd > ./w1_md3_resid_247.namd.out &
$MPI -np 1 --hostfile host.2 $NAMD ./w1_md3_resid_251.namd > ./w1_md3_resid_251.namd.out &
..

and so on.