Orca

Orca is a free software for all types of QM calculations.
Documentation and tutorials are here: https://www.orcasoftware.de/tutorials_orca

The current version is 5.0.3.
It is installed on Aurora:
module add GCC/11.2.0  OpenMPI/4.1.1 ORCA/5.0.3-static
Then, it is run by
orca input_file >output

Avogadro is a good option to illustrate Orca output



This is a simple sample input file:

! RHF def2-SVP          # Level of theory.
! SP                             # Single-point energy calculation; it is default or
! OPT                          # Geometry optimisation

* xyz 0 1                     # Charge, and multiplicity followed by coordinates in Å (can be changed to a.u. by %coords Units bohrs)
h           1.57623125918282     -1.40098816005358      1.92944524289998
c           3.11804788185000     -1.26044723466300      3.33347664459600
h           4.63927730299500     -2.45475405971100      2.62293967273200
h           3.85126156558200      0.66329382213900      3.40150678020000
h           2.59270405690800     -1.91429242685700      5.21564372964000
*

Alternatively, internal coordinates can be used:
* int 0 2
O 0 0 0 0.0       0.0 0.0
H 1 0 0 0.9903 0.0 0.0
*

Alternatively, an xyz file can be used:
* xyzfile 0 2 hydroxide.xyz

File:
2 # number of atoms; next line blank or title

0
O 0 0 0
H 0 0 0.9903

Alternatively, an pdb file can be used:
* pdbfile 0 2 hydroxide.pdb

Input file is not case sensitive.

Note that orca number atoms starting with 0, which may be very confusing in the beginning.

Options

Use RI and RIJCOSX (exchange)
!B3LYP def2-SVP def2/J RIJDX RIJCOSX
In fact, this is default for DFT; to turn it off, use !NORI and !NOCOSX

Dispersion correction
!D3 or !D4

I
ncrease amount printed out (e.g. to print orbitals)
!HF def2-SVP Largeprint

Frequency calculation
!FREQ
!TightOpt or !VeryTightOpt may remove imaginary freqs

Implicit solvent
!CPCM(solvent)
or
%CPCM
 EPSILON 80
 REFRAC 1.33
END
%CPCM SMD TRU
 SMDSolven "solvent"
END

Relativistic corrections
!B3LYP ZORA ZORA-def2-TVP RIJDX SARC/J

DLPNO CC
!DLPNO-CCSD(T) def2-TZVPP def2-TZVPP/C

Change maximum number of geometry steps

%geom
maxiter 1              
end

Constraints
%geom
Constraints           
{B 0 1 1.25 C}.    # Bond length constraint
end

Cartesian optimisation
! COpt

SCF options
%scf
MaxIter 300
CNVDIIS 1
CNVSOSCF 1
end

Level shift
%scf
 CNVShift true # default = true
 LShift 0.1 # default = 0.25
 ShiftErr 0.1 #default = 0.0
# more convenient:
 Shift Shift 0.1 ErrOff 0.1 end
end

Output options
%output
print[p_mos] true
print[p_basis] 5
end

Paralell calculations
%pal
nprocs 20               #Maximum number of cores of your machine.
end

Point charges with file reference
%pointcharges "pointcharges.pc"

File pointcharges.pc
418 # number of point charges
 0.294300             6.494988     -4.096926     -5.179739  # charge and coordinates
 0.164200             7.320798     -3.807798     -6.874823
 0.164200             6.417509     -5.943188     -4.694079
...
No special ending
Atomic units

Geometry options
%geom
 MaxIter 200
 TS_search EF
 # ! OptTs
 TolE 5e-6
 TolRMSG 1e-4
 TolMaxG 3e-4
 TolRMSD 2e-3
 TolMaxD 4e-3
 inhess GFNFF
end


%MaxCore 2000