From Documentation
Jump to: navigation, search
ORCA
Description: An ab initio, DFT and semiempirical SCF-MO package.
SHARCNET Package information: see ORCA software page in web portal
Full list of SHARCNET supported software


Introduction

ORCA is an ab initio, DFT and semiempirical SCF-MO package. It 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.

Version Selection

Current version is 3.0, a binary version from https://orcaforum.cec.mpg.de/ To use ORCA, you can add the following lines into your shell configuration file such as the .bash_profile file under your /home

module unload intel openmpi
module load open64/5.0 openmpi/open64/1.6.2
module load orca/3.0

save the .bash_profile file, logout and login again. Type 'which orca' should give:

/opt/sharcnet/orca/3.0/orca

Job Submission

  • Prepare your own input file (test.inp used in the Examples below) under your /work or /scratch directory.
  • Submit your job using sqsub (type 'sqsub -h' for more options) on cluster from the input file directory

Serial job

sqsub -r 1.0d -o test.out /opt/sharcnet/orca/3.0/orca test.inp

Parallel ORCA job

  • To run the code with input file test.inp, here is an example to use 4 cpus, 1.5g memory per cpu, 1 day walltime
sqsub -q mpi -n 4 -N 1 --nompirun --mpp=1.5g -r 1.0d -o test.out /opt/sharcnet/orca/3.0/orca test.inp

Example Job

Input file for serial job

 ! RHF TightSCF PModel
 !opt

 * xyz 0 1
  C 0.000000 0.000000 0.000000
  C 0.000000 0.000000 1.400000
  C 1.212436 0.000000 2.100000
  C 2.424871 0.000000 1.400000
  C 2.424871 0.000000 0.000000
  C 1.212436 0.000000 -0.700000
  H -0.943102 0.000000 1.944500
  H 1.212436 0.000000 3.189000
  H 3.367973 0.000000 1.944500
  H 3.367973 0.000000 -0.544500
  H 1.212436 0.000000 -1.789000
  H -0.943102 0.000000 -0.544500
 *

test run can be found in /home/jemmyhu/tests/test_ORCA/serial/

Input file for parallel job

  • Parallel ORCA, sample input to use 4 cpus
 %pal nprocs 4 end
 ! RHF TightSCF PModel
 !opt

 * xyz 0 1
  C 0.000000 0.000000 0.000000
  C 0.000000 0.000000 1.400000
  C 1.212436 0.000000 2.100000
  C 2.424871 0.000000 1.400000
  C 2.424871 0.000000 0.000000
  C 1.212436 0.000000 -0.700000
  H -0.943102 0.000000 1.944500
  H 1.212436 0.000000 3.189000
  H 3.367973 0.000000 1.944500
  H 3.367973 0.000000 -0.544500
  H 1.212436 0.000000 -1.789000
  H -0.943102 0.000000 -0.544500
 *

test run can be found in /home/jemmyhu/tests/test_ORCA/parallel/

General Notes

1) To run parallel ORCA jobs, you need to specify how many cpus to use at the very beginning of the .inp file, for 4 cpus, it's

%pal nprocs 4 end

2) a few things for sqsub command

2a) need to use the same number of cpus in sqsub -q mpi -n * --nompirun ... as specified in the .inp
2b) need to use --nompirun in sqsub
2c) need to use the full PATH to orca (path setting or aliases will not work) /opt/sharcnet/orca/3.0/orca

3) better to run multi-cpu jobs on one node as across nodes will run slower, sqsub command can be

sqsub -q mpi -n 4 -N 1 --nompirun --mpp=1.5g -r 1.0d -o test.out /work/jemmyhu/software/ORCA/3.0/orca test.inp

4) for cpus on one node, the maximum cpus to use is 8 on saw, 16 on orca (more cpus on orca will wait in the queue for longer time)


References

o Orca Homepage
https://orcaforum.cec.mpg.de/