ORCA¶
Introduction¶
ORCA is a flexible, efficient, and easy-to-use general-purpose tool for quantum chemistry with specific emphasis on spectroscopic properties of open-shell molecules. It features a wide variety of standard quantum chemical methods ranging from semiempirical methods to DFT to single- and multireference correlated ab initio methods. It can also treat environmental and relativistic effects.
Installed Versions¶
For the current list of installed versions, use:
$ ml av orca
Serial Computation With ORCA¶
You can test a serial computation with this simple input file.
Create a file called orca_serial.inp and paste into it the following ORCA commands:
! HF SVP
* xyz 0 1
C 0 0 0
O 0 0 1.13
*
Next, create a Slurm submission file for Karolina cluster (interactive job can be used too):
#!/bin/bash
#SBATCH --job-name=ORCA_SERIAL
#SBATCH --nodes=1
#SBATCH --ntasks-per-node=128
#SBATCH --partition=qexp
#SBATCH --account=OPEN-0-0
ml ORCA/5.0.1-OpenMPI-4.1.1
srun orca orca_serial.inp
Submit the job to the queue. After the job ends, you can find an output log in your working directory:
sbatch submit_serial.slurm
1417552
$ ll ORCA_SERIAL.*
-rw------- 1 user user 0 Aug 21 12:24 ORCA_SERIAL.e1417552
-rw------- 1 user user 20715 Aug 21 12:25 ORCA_SERIAL.o1417552
$ cat ORCA_SERIAL.o1417552
*****************
* O R C A *
*****************
--- An Ab Initio, DFT and Semiempirical electronic structure package ---
#######################################################
# -***- #
# Department of molecular theory and spectroscopy #
# Directorship: Frank Neese #
# Max Planck Institute for Chemical Energy Conversion #
# D-45470 Muelheim/Ruhr #
# Germany #
# #
# All rights reserved #
# -***- #
#######################################################
Program Version 5.0.1 - RELEASE -
...
****ORCA TERMINATED NORMALLY****
TOTAL RUN TIME: 0 days 0 hours 0 minutes 1 seconds 47 msec
Running ORCA in Parallel¶
Your serial computation can be easily converted to parallel.
Simply specify the number of parallel processes by the %pal directive.
In this example, 4 nodes, 128 cores each are used.
Warning
Do not use the ! PAL directive as only PAL2 to PAL8 is recognized.
! HF SVP
%pal
nprocs 512 # 4 nodes, 128 cores each
end
* xyz 0 1
C 0 0 0
O 0 0 1.13
*
You also need to edit the previously used Slurm submission file. You have to specify number of nodes, cores, and MPI-processes to run:
#!/bin/bash
#SBATCH --job-name=ORCA_PARALLEL
#SBATCH --nodes=4
#SBATCH --ntasks-per-node=128
#SBATCH --partition=qexp
#SBATCH --account=OPEN-0-0
ml ORCA/5.0.1-OpenMPI-4.1.1
srun orca orca_parallel.inp > output.out
Note
When running ORCA in parallel, ORCA should NOT be started with mpirun (e.g. mpirun -np 4 orca, etc.)
like many MPI programs and has to be called with a full pathname.
Submit this job to the queue and see the output file.
$ srun submit_parallel.slurm
1417598
$ ll ORCA_PARALLEL.*
-rw------- 1 user user 0 Aug 21 13:12 ORCA_PARALLEL.e1417598
-rw------- 1 user user 23561 Aug 21 13:13 ORCA_PARALLEL.o1417598
$ cat ORCA_PARALLEL.o1417598
*****************
* O R C A *
*****************
--- An Ab Initio, DFT and Semiempirical electronic structure package ---
#######################################################
# -***- #
# Department of molecular theory and spectroscopy #
# Directorship: Frank Neese #
# Max Planck Institute for Chemical Energy Conversion #
# D-45470 Muelheim/Ruhr #
# Germany #
# #
# All rights reserved #
# -***- #
#######################################################
Program Version 5.0.1 - RELEASE -
...
************************************************************
* Program running with 64 parallel MPI-processes *
* working on a common directory *
************************************************************
...
****ORCA TERMINATED NORMALLY****
TOTAL RUN TIME: 0 days 0 hours 0 minutes 11 seconds 859 msec
You can see, that the program was running with 512 parallel MPI-processes. In version 5.0.1, only the following modules are parallelized:
- ANOINT
- CASSCF / NEVPT2
- CIPSI
- CIS/TDDFT
- CPSCF
- EPRNMR
- GTOINT
- MDCI (Canonical-, PNO-, DLPNO-Methods)
- MP2 and RI-MP2 (including Gradient and Hessian)
- MRCI
- PC
- ROCIS
- SCF
- SCFGRAD
- SCFHESS
- SOC
- Numerical Gradients and Frequencies
Example Submission Script¶
The following script contains all of the necessary instructions to run an ORCA job,
including copying of the files to and from /scratch to utilize the InfiniBand network:
#!/bin/bash
#SBATCH --account=OPEN-00-00
#SBATCH --job-name=example-CO
#SBATCH --partition=qexp
#SBATCH --nodes=2
#SBATCH --ntasks-per-node=128
#SBATCH --cpus-per-task=1
#SBATCH --time=00:05:00
ml purge
ml ORCA/5.0.1-OpenMPI-4.1.1
echo $SLURM_O_WORKDIR
cd $SLURM_O_WORKDIR
# create /scratch dir
b=$(basename $SLURM_O_WORKDIR)
SCRDIR=/scratch/project/OPEN-00-00/$USER/${b}_${SLURM_JOBID}/
echo $SCRDIR
mkdir -p $SCRDIR
cd $SCRDIR || exit
# get number of cores used for our job
ncpus=$(sacct -j 727825 --format=AllocCPUS --noheader | head -1)
### create ORCA input file
cat > ${SLURM_JOBNAME}.inp <<EOF
! HF def2-TZVP
%pal
nprocs $ncpus
end
* xyz 0 1
C 0.0 0.0
0.0
O 0.0 0.0
1.13
*
EOF
###
# copy input files to /scratch
cp -r $SLURM_O_WORKDIR/* .
# run calculations
$(which orca) ${SLURM_JOBNAME}.inp > $SLURM_O_WORKDIR/${SLURM_JOBNAME}.out
# copy output files to home, delete the rest
cp * $SLURM_O_WORKDIR/ && cd $SLURM_O_WORKDIR
rm -rf $SCRDIR
exit
Register as User¶
You are encouraged to register as a user of ORCA here in order to take advantage of updates, announcements, and the users forum.
Documentation¶
A comprehensive manual is available online for registered users.