Q-Chem is a comprehensive ab initio quantum chemistry package. Its capabilities range from the highest performance DFT/HF calculations to high level post-HF correlation methods.

The QChem module is available on the Itasca and Cascade clusters.

To run the application interactively in the Linux environment run the commands:

module load qchem
qchem water.in

Other versions of qchem are available. The "serial" type installations support single threaded and multi-threaded (OpenMP) execution. The "parallel" type installations support MPI execution (via a QChem-internal version of MPICH). The naming scheme for each type follows: 

qchem/serial (default)

To run QChem in multi-threaded (OpenMP) mode, specify the number of threads with "-nt": 

qchem -nt 4 DFT_glutamine.in output.out

The following example demonstrates how to run Q-Chem with 16 MPI processes:

#!/bin/bash -l

#PBS -l walltime=01:00:00,mem=21gb,nodes=2:ppn=8

#PBS -m abe

module load qchem/4.1_parallel

cat $PBS_NODEFILE               

# Uncomment these lines to get 1 proc per node (the ppn=8 must

# remain above)

#cat $PBS_NODEFILE | sort -u > $PBS_O_WORKDIR/machinefile

#export PBS_NODEFILE=$PBS_O_WORKDIR/machinefile

NN=`cat $PBS_NODEFILE | wc -l`

echo "Launching job for NN=$NN processes"


# Sample input files are available with each module

cp /soft/qchem/3.2_parallel/samples/DFT_glutamine.in .

qchem -pbs -np $NN $PBS_O_WORKDIR/DFT_glutamine.in \



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