ORCA
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ORCA4

TiO2 clusters

Input

Geometry file

System Charge Multiplicity
neutral molecule 0 1
protonated PAHs C16H15+ 1 1
cation H2O+ 1 2
radical cation PAHs C16H14+ 1 2

spin multiplicity

$$\text{multiplicity} = \text{number of } \alpha \text{ electrons} - \text{number of } \beta \text{ electrons} + 1$$ - When #electrons is odd, then multiplicity must be even (2, 4, 6, ...). - When #electrons is even, then multiplicity must be old (1, 3, 5, ...).

RI

RIJCOSX

meta-GGA

Broken symmetry

Tips

Parallel run on multiple nodes

One has to create JOBNAME.nodes in the running directory to run on multiple nodes. echo $SLURM_NODELIST >> JOBNAME.nodes will create s31n[07-09] which cannot be recognized by ORCA. The following script gives the correct multiple nodes setting.

#SBATCH --nodelist=s31n[07-09]
#SBATCH --ntasks=36
#SBATCH --ntasks-per-node=12
#SBATCH --cpus-per-task=1

# change directory to the local scratch-directory, and run:
cd /scratch/$SLURM_JOB_ID
cat > orca.nodes <<!
s31n07 slots=12
s31n08 slots=12
s31n09 slots=12
!

Warnings

WARNING: For RIJCOSX frequencies GRIDX4 or larger grids are recommended

Errors

spin

[file orca_main/mainfcts.cpp, line 625]: Error : multiplicity (2) is even and number of electrons (204) is even -> impossible

Geometry

----------------------------------------------------------------------------
                               ERROR !!!
   The optimization did not converge but reached the maximum 
   number of optimization cycles.
   As a subsequent Frequencies calculation has been requested
   ORCA will abort at this point of the run.
   Please restart the calculation with the lowest energy geometry and/or
   a larger maxiter for the geometry optimization.
----------------------------------------------------------------------------
  [file orca_main/run.cpp, line 10680]: ORCA finished with error return - aborting the run