ORCA

Access to Orca

Access to Orca requires the user to register at the Orca forum, https://orcaforum.kofo.mpg.de/. There you will agree to the EULA and receive a confirmation email. Please raise a ticket via https://www.imperial.ac.uk/admin-services/ict/self-service/research-support/rcs/get-support/contact-us/ giving a screen shot of this email and ask to be added to the Orca access list.

Versions available

There are a few versions of Orca installed on HPC, use the module system to list and then load the desired version

$ module av orca
---------------------------------------------------------------------------- /apps/modules/4.7.1/modulefiles ----------------------------------------------------------------------------
orca/2.6.35  orca/2.6.71beta  orca/2.7.0b  orca/2.8.0  orca/2.9.1(default)  orca/3.0.0  orca/3.0.2  orca/4.0.0  orca/4.2.1  orca/5.0.1  orca/5.0.3  orca/r1038

Simple job

To submit a job to the HPC system, you need to create a job submission script that specifies the necessary input files, the ORCA version, and any required input parameters. Here's a simple example you can use to get started:

#!/bin/bash
#PBS -N orca_job
#PBS -l select=1:ncpus=1:mem=8gb
#PBS -l walltime=01:00:00
#This requests 1 cpu on a single node. 

# Load the ORCA module
module load orca

# Change to the job's working directory
cd $PBS_O_WORKDIR

# Run ORCA
orca my_input_file.inp > orca_output.log
  1. Replace my_input_file.inp with the name of your ORCA input file.
  2. In the module load command, replace orca with the name of the ORCA module as it appears in the module av, for example module load orca/5.0.3
  3. Modify the #PBS directives as needed to specify the resources required by your job, such as the number of nodes, cores, and walltime. Have a look at the Queueing System pages for more information.

Save this as orca_job.pbs and then submit the job by running the following command:

qsub orca_job.pbs

This will submit the job to PBSPro. The job will run the ORCA executable with the specified input file, and any output will be written to the orca_output.log file in the job's working directory. For more information on using Orca have a look at the official documentation: https://www.orcasoftware.de/tutorials_orca/