ORCA - An ab initio, DFT and semiempirical SCF-MO package.

Orca is as quantum chemistry package developed by Prof. Frank Neese. It offers a broad range of methods ranging from semi empirics overt DFT to HF and post HF methods. Please refer to the Orca web page and the input manual for details. 

When using Orca please abide to the rules set by the user licence agreement


LRZ has licensed ORCA to academic users under an installation and maintenance agreement; under this agreement, usage of the software is only allowed for registred users in the ORCA forum.

Before using ORCA on the LRZ HPC systems, the following steps must be performed:

  1. The user applies by contacting LRZ HPC support, providing the following information: name, affiliation (working group), user account(s) under which you access the LRZ systems, and ORCA registered user-ID.  

  2. LRZ checks back with the ORCA team whether your name is registered, upon positive feedback, access to the software is given by LRZ.

Running Orca at LRZ

(Please note that there will be no more software updates for the CoolMUC3  system. As the system will be switched off soon, the usage of ORCA on it is limited, and it's at your own risk.)

After login to the system please load the module environment appropriate via:

module load orca  

The available versions are displayed with:

module avail orca

Batch jobs for Serial or Parallel ORCA

Submit the follwoing script:

Linux-Cluster or SuperMUC-NG  (SLURM)

#SBATCH -J job_name
#SBATCH -o ./%x.%j.%N.out
#SBATCH --get-user-env
#SBATCH --clusters=cm2_tiny
#SBATCH --partition=cm2_tiny
#SBATCH --nodes=1-1
#SBATCH --cpus-per-task=28
# 56 is the maximum reasonable value for CooLMUC-2
#SBATCH --mail-type=end
#SBATCH --mail-user=insert_your_email_here
#SBATCH --export=NONE
#SBATCH --time=08:00:00
module load slurm_setup

module load orca

$ORCA_BIN/orca /path/to/your/job.inp >& job.out

More job script examples can be found here: Example+parallel+job+scripts+on+the+Linux-Cluster

Note that for parallel runs you have to specify the number of MPI processes in the input file. Add the section

  nprocs 8

here to input_par.in.

Submit the job script using sbatch command, e.g., assume the job script name is name-job.sh,

Then submit the job script using, sbatch commands.

% sbatch  name-job.pbs

here are many other parameters to the batch system at LRZ. For more details see Batch Queuing and Job Policies


After execution of "module load gamess", the environment variable documentation points to a directory containing the ORCA documentation as it comes with the source code:

ls -C  $ORCA_DOC

Other format of the documentation and more information may be found on the ORCA Home Page: https://orcaforum.kofo.mpg.de/app.php/portal


If you have any questions or problems with ORCA installed on the different LRZ platforms, please don't hesitate to conatct the LRZ HPC support staff.