ORCA
ORCA is an ab initio quantum chemistry program package that contains modern electronic structure methods including density functional theory, many-body perturbation, coupled cluster, multireference methods, and semi-empirical quantum chemistry methods. Its main field of application is larger molecules, transition metal complexes, and their spectroscopic properties.
ORCA requires a license per individual or research group (cf. https://cec.mpg.de/orcadownload/ or the ORCA forum https://orcaforum.kofo.mpg.de/). Once you can proof that you are eligible, contact support-hpc@fau.de for activation of the ORCA module.
Availability / Target HPC systems
- throughput cluster Woody and TinyEth/TinyFAT
- owing to its limited scalability, ORCA is not suited for the parallel computers
New versions of ORCA are installed by RRZE upon request with low priority if the users provide the installation files.
Notes
orca
has to be called with the full path otherwise parallel runs may fail.- The
orca
module will take care of loading an appropriateopenmpi
module, too. - ORCA often results in massive IO (“communication through files??”); thus, put temporary files into
/dev/shm
(RAM disk) or local scratch directory.
Sample job scripts
#!/bin/bash -l
#PBS -lnodes=1:ppn=4,walltime=10:00:00
#PBS -N my-orca
#PBS -j eo
cd $PBS_O_WORKDIR
module add orca/4.1.1
### No mpirun required as ORCA starts the parallel processes internally as needed.
### The number of processes is specified in the input file using '%pal nprocs # end'
${ORCABASE}/orca orca.inp "optional openmpi arguments"
Further information
- https://orcaforum.kofo.mpg.de/
- note in the ORCA forum on improving MKL performance on AMD Epyc processors: https://orcaforum.kofo.mpg.de/viewtopic.php?f=8&t=3340&hilit=mkl&start=20
Mentors
- please volunteer!