A flexible, efficient and easy-to-use general purpose tool for quantum chemistry with specific emphasis on spectroscopic properties.
ORCA requires an environment module
In order to use ORCA, you must first load the appropriate environment module:
module load gnu openmpi orca
ORCA is computational chemistry program focusing on quantum chemistry applications. The program is designed for modeling electronic structures as well as spectroscopic properties of molecules. The program contains a variety of different methods for performing such simulations.
Using ORCA on RCC Resources#
The ORCA quantum chemistry tool is available on the HPC cluster for parallel processing of ORCA jobs.
In order to use ORCA, you must load the
To load ORCA v4.1.2, you'll need to load the old OpenMPI v2.1.0 module:
Submitting a Job#
Following is a sample ORCA input parameter file. Note the line
! PAL``x (x = 2 in the example) at the beginning
where x is the number of parallel processes you would like to run simultaneously.
Create a SLURM submission script. For example:
Note that ORCA may throw an error relating to an inability to access or execute an executable file. If this occurs, then you will need to provide the entire absolute file path when calling ORCA. See the Troubleshooting section below for details.
Testing ORCA scripts#
You can also run ORCA scripts on the HPC login nodes for testing purposes only. Ensure that you remove the
! PAL``x line:
Unload the conflicting module first, for example, by running
module purge before you load the ORCA module.
If ORCA throws an error relating to an inability to access or execute an executable file, the way to fix it, according to the ORCA Users Manual on the official website, is to type the entire path to ORCA on the HPC before the .inp file when calling the program. For example:
$PATH is the complete absolute file path which can be found using
which orca. Once
which orca is run, just
copy and paste the absolute file path it returns into the command line or the line in your SLURM submission script
that calls ORCA and type the input file's name as shown above.