ORCA is a flexible, efficient and easy-to-use general purpose tool for quantum chemistry
with specific emphasis on spectroscopic properties of open-shell molecules.
It features a wide variety of standard quantum chemical methods ranging from semiempirical methods to DFT to single-
and multireference correlated ab initio methods.
It can also treat environmental and relativistic effects.

Software Category: chem

For detailed information, visit the ORCA

Available Versions

The current installation of ORCA
incorporates the most popular packages. To find the available versions and learn how to load them, run:

module spider orca

The output of the command shows the available ORCA
module versions.

For detailed information about a particular ORCA
module, including how to load the module, run the module spider command with the module’s full version label. For example:

module spider orca/5.0.2
ModuleVersion Module Load Command
orca5.0.2 module load orca/5.0.2
orca5.0.4 module load orca/5.0.4

License and Permission

We have an “ACADEMIA” license. Usage is restricted to academic purposes. Please contact us if you need access to the software.

Slurm script template

Below is a Slurm script template. Please note that:

  • Loading the orca module will automatically load gcc and openmpi. Do not load the latter manually.
  • For your convenience we have defined the environment variable orcadir in the module.
  • The full path to the executable orca is thus $orcadir/orca.
  • Do not use srun/mpirun. The software will take care of MPI.
#SBATCH -A mygroup    # your allocation account
#SBATCH -p standard   # partition
#SBATCH -N 1          # number of nodes
#SBATCH -n 10         # number of tasks
#SBATCH -t 24:00:00   # time

module purge
module load orca
$orcadir/orca my.inp > my.out

Submit the job in the same directory as my.inp.


For larger calculations, you may run on multiple nodes. The following example will run on a total of 120 cores:

#SBATCH -A mygroup            # your allocation account
#SBATCH -p parallel           # partition
#SBATCH -N 3                  # number of nodes
#SBATCH --ntasks-per-node=40  # number of tasks
#SBATCH -t 24:00:00           # time

module purge
module load orca
$orcadir/orca my.inp > my.out

Important notes:

  • The nprocs in *.inp should be equal to the total number of cores requested in your Slurm script.
  • Do not run multi-node ORCA jobs from research standard storage /nv. (See here.) We recommend scratch.


For more information please visit: