Orca

Orca is a quantum chemistry software from the Max-Planck-Institut für Kohlenforschung.

Orca on Euler¶

Version	Module load command
6.1.1	`module load stack/2024-06 openmpi/4.1.6 orca/6.1.1`
6.1.0	`module load stack/2024-06 openmpi/4.1.6 orca/6.1.0`
6.0.1	`module load stack/2024-06 openmpi/4.1.6 orca/6.0.1`
6.0.0	`module load stack/2024-06 openmpi/4.1.6 orca/6.0.0`
5.0.4	`module load stack/2024-06 openmpi/4.1.6 orca/5.0.4`

Orca's end user license agreement (EULA) requires all users to be register at the ORCA portal: https://orcaforum.kofo.mpg.de/app.php/portal

After registeration, use the command:

get-access orca

It checks for the existence of your ORCA account and grants you access if successful.

Example execution¶

Create a file input.inp with the following content:

# Input file for the goldchloride example:
! BP ECP{def2-TZVP,def2-TZVP/J} def2-tzvp def2-tzvp/j tightscf opt
%pal nprocs 4
    end
* xyz -2 2
Au  0   0   0
Cl  2.5 0   0
Cl -2.5 0   0
Cl  0   2.5 0
Cl  0  -2.5 0
*

Load the Orca module and run the job via Slurm:

module load stack/2024-06 openmpi/4.1.6 orca/6.1.0
srun orca input.inp > output.out

Parallel execution¶

It is not sufficient to request multiple cores from the batch system to run Orca in parallel. You must also specify in the input file how many cores should be used:

%pal nprocs 4