Orca/Parallel

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If you would like to run orca in parallel, then you need to load the open_mpi/1.6.5 module, before you load the orca module. For instance, when using orca 3.0.3, then you would need to load the following modules:

module load open_mpi/1.6.5 orca/3.0.3

Further more you also need to add a line to the orca input file to specify the number of cores that should be used. For a 4 core job, you would add

%pal nprocs 4

To your orca input file. The example input file provided on this wiki page would then change to

* Updated 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
*

and the submission command would be

bsub -n 4 -W 1:00 -R "rusage[mem=2048]" "orca test1.inp > test1.out"

Please note that you also need to request 4 cores from the batch system, when submitting the job. It is not sufficient to just change the orca input file.