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 --partition=qcpu_exp
#SBATCH --time=1:00:00
#SBATCH --account=OPEN-0-0
ml ORCA/6.0.0-gompi-2023a-avx2
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 *
*****************
#########################################################
# -***- #
# Department of theory and spectroscopy #
# #
# Frank Neese #
# #
# Directorship, Architecture, Infrastructure #
# SHARK, DRIVERS #
# Core code/Algorithms in most modules #
# #
# Max Planck Institute fuer Kohlenforschung #
# Kaiser Wilhelm Platz 1 #
# D-45470 Muelheim/Ruhr #
# Germany #
# #
# All rights reserved #
# -***- #
#########################################################
Program Version 6.0.0 - RELEASE -
...
****ORCA TERMINATED NORMALLY****
TOTAL RUN TIME: 0 days 0 hours 0 minutes 0 seconds 980 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, 1 node, 16 cores are used.
Warning
Do not use the ! PAL directive as only PAL2 to PAL8 is recognized.
! HF SVP
%pal
nprocs 16
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=1
#SBATCH --ntasks-per-node=16
#SBATCH --partition=qcpu_exp
#SBATCH --account=OPEN-0-0
#SBATCH --time=1:00:00
ml ORCA/6.0.0-gompi-2023a-avx2
$(which 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.
$ sbatch submit_parallel.slurm
Submitted batch job 2127305
$ cat output.out
*****************
* O R C A *
*****************
#########################################################
# -***- #
# Department of theory and spectroscopy #
# #
# Frank Neese #
# #
# Directorship, Architecture, Infrastructure #
# SHARK, DRIVERS #
# Core code/Algorithms in most modules #
# #
# Max Planck Institute fuer Kohlenforschung #
# Kaiser Wilhelm Platz 1 #
# D-45470 Muelheim/Ruhr #
# Germany #
# #
# All rights reserved #
# -***- #
#########################################################
Program Version 6.0.0 - RELEASE -
...
************************************************************
* Program running with 16 parallel MPI-processes *
* working on a common directory *
************************************************************
...
****ORCA TERMINATED NORMALLY****
TOTAL RUN TIME: 0 days 0 hours 0 minutes 17 seconds 62 msec
You can see, that the program was running with 16 parallel MPI-processes. In version 6.0.0, only the following modules are parallelized:
- AUTOCI
- CASSCF / NEVPT2 / CASSCFRESP
- CIPSI
- CIS/TDDFT
- GRAD (general Gradient program)
- GUESS
- LEANSCF (memory conserving SCF solver)
- MCRPA
- MDCI (Canonical- and DLPNO-Methods)
- MM
- MP2 and RI-MP2 (including Gradients)
- MRCI
- PC
- PLOT
- PNMR
- POP
- PROP
- PROPINT
- REL
- ROCIS
- SCFGRAD
- SCFRESP (with SCFHessian)
- STARTUP
- VPOT
- Numerical Gradients, Frequencies, Overtones-and-Combination-Bands
- VPT2
- NEB (Nudged Elastic Band
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.