ORCA

https://www.faccts.de/docs/orca/6.0/manual/
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ORCA is an ab initio, DFT, and semiempirical SCF-MO package for quantum chemistry calculations...
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### Example Property Structure

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/property_file.md.txt

Demonstrates the basic structure of a property in the .txt format, starting with '$' and ending with '$End'.

```text
$SCF_Energy
   &GeometryIndex 1
   &ListStatus       OUT
   &SCF_ENERGY [&Type "Double"]      -1.1271129230772137e+00
$End
```

--------------------------------

### Example JSON Output for Property File

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/orca_2json.md.txt

The start of a JSON file generated from an ORCA property file.

```json
This is the start of a JSON file generated from an ORCA property file.
```

--------------------------------

### QDPT Computation Status Output

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/qdpt_magnetic_properties.md.txt

Example of the console output indicating the start of QDPT Hamiltonian computation.

```text
----------------------------------
QDPT WITH CASSCF/NEVPT2/MRCI... DIAGONAL ENERGIES
----------------------------------


*************************************
COMPUTING QDPT HAMILTONIAN
*************************************

*************************************
Doing QDPT with ONLY SOC!
*************************************
```

--------------------------------

### Example Command with Modifiers and Arguments

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/moldyn.md.txt

A concrete example of the 'Dump' command, showing its non-optional argument and two modifiers with their respective arguments.

```orca
%md
  Dump Position Stride 1 Filename "trajectory.xyz"
end
```

--------------------------------

### Example QM/QM2/MM Input

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/qmmm.md.txt

A complete example input file for a QM/QM2/MM calculation, specifying ORCAFF parameters, atom selections, and PDB file.

```orca
!QM/HF-3c/MM Opt B3LYP def2-TZVP def2/J NumFreq
%qmmm
 ORCAFFFilename "peptideChain.ORCAFF.prms" 
 QMAtoms {16:33 68:82} end
 QM2Atoms {0:12 83:104} end
 ActiveAtoms { 0:38 65:120} end
 Charge_Medium 0
end
*pdbfile -1 1 peptideChain.pdb
```

--------------------------------

### Example Property Component

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/property_file.md.txt

Illustrates a single component within a property, starting with '&' followed by the component name and its value.

```text
   &SCF_ENERGY [&Type "Double"]      -1.1271129230772137e+00
```

--------------------------------

### Custom Solvent XYZ File Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/solvator.md.txt

An example of the content for a custom solvent .xyz file, defining the atomic coordinates of isopropanol.

```xyz
12
0 1
C         -3.79410        2.24670       -0.09622
C         -3.45574        0.76660       -0.18820
H         -2.94382        2.85306       -0.42645
H         -4.00575        2.53923        0.93817
H         -4.66172        2.49512       -0.71492
C         -4.60559       -0.10847        0.28691
H         -4.84802        0.09429        1.33594
H         -4.32886       -1.16657        0.22730
H         -5.50341        0.05251       -0.31744
O         -2.30376        0.49878        0.60542
H         -3.20686        0.51239       -1.22373
H         -2.51694        0.72259        1.52758
```

--------------------------------

### bt-PNO-IP-EOM-CCSD Input Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/eomcore.md.txt

Example input file for bt-PNO-IP-EOM-CCSD.

```orca
!bt-PNO-IP-EOM-CCSD ExtremeSCF cc-pvtz cc-pvtz/c 
!NoFrozencore
%maxcore 5000

%mdci
nroots 4
CVSORB 0,3
FollowCIS true
CVSEP true
DoCVS true
DoCore true
DoRECAN true # recanonilize the occupied space before the EOM step
corehole 0
printlevel 3
maxiter 500
end

*xyz 0 1
 C             -6.7624010562   0.1328615492   0.0389382700

```

--------------------------------

### ORCA Docker Output Header

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/docker.md.txt

This is an example of the initial output from the ORCA Docker, indicating the start of the process, the guest file being read, and the optimization of host and guest structures.

```text
                               ***************
                               * ORCA Docker *
                               ***************       
   
Reading guests from file             water.xyz
Number of structures read from file  1
Charge and multiplicity of guest     from file
Docking approach                     independent
Docking level                        normal
Optimizing host                      .... -5.070544 Eh
Optimizing guest                     .... -5.070544 Eh

```

--------------------------------

### Subtractive QM/QM2 Product Structure Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/qmmm.md.txt

Example of a product structure file (XYZ format) used in conjunction with a subtractive QM/QM2 calculation.

```xyz
```{literalinclude} ../../orca_working_input/propionicAcid_prod.xyz
:language: orca
```
```

--------------------------------

### orca_loc Input File Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/utilities.md.txt

Example of an input file for the orca_loc utility. Specify input/output GBW files, orbital ranges, and the localization method.

```shell
Myjob.gbw     # input orbitals 
Myjob.loc.gbw # output orbitals 
10            # orbital window: first orbital to be localized e.g. first active 
15            # orbital window: last orbital to be localized e.g. last active 
0             # localization method:
              # 1=PIPEK-MEZEY,2=FOSTER-BOYS,3=IAO-IBO,4=IAO-BOYS,5=NEW-BOYS,6=AHFB
```

--------------------------------

### CASSCF NTO Output Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/energygradients.md.txt

Example output showing calculated Natural Transition Orbitals and saved files.

```orca
==========================================
CASSCF Natural Transition Orbitals
==========================================

------------------------------------------------
NATURAL TRANSITION ORBITALS FOR STATE     1 1A  
------------------------------------------------

STATE    1 1A  :  E=   0.141508 au      3.851 eV    31057.3 cm**-1

Threshold for printing occupation numbers 1.0000e-04

     0  : n=  1.30882812
     1  : n=  0.02641080

=> Natural Transition Orbitals (donor   ) were saved in Test-CASSCF.H2CO-1.casscf.1-1A_nto-donor.gbw
=> Natural Transition Orbitals (acceptor) were saved in Test-CASSCF.H2CO-1.casscf.1-1A_nto-acceptor.gbw

------------------------------------------------
NATURAL TRANSITION ORBITALS FOR STATE     2 1A  
------------------------------------------------

STATE    2 1A  :  E=   0.453905 au     12.351 eV    99620.7 cm**-1

Threshold for printing occupation numbers 1.0000e-04

     0  : n=  1.30519478
     1  : n=  0.24869813
     2  : n=  0.00471742

=> Natural Transition Orbitals (donor   ) were saved in Test-CASSCF.H2CO-1.casscf.2-1A_nto-donor.gbw
=> Natural Transition Orbitals (acceptor) were saved in Test-CASSCF.H2CO-1.casscf.2-1A_nto-acceptor.gbw
```

--------------------------------

### SORCI Output Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/mrci.md.txt

Example output showing state energies for a SORCI calculation.

```orca
State Mult Irrep Root Block    mEh          eV      1/cm
  0    1    A1    0    0      0.000      0.000       0.0
  1    3    A2    0    2    145.494      3.959   31932.3
  2    1    A2    0    1    162.222      4.414   35603.6
```

--------------------------------

### ORCA Input File Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/model.md.txt

This is an example of an ORCA input file, likely containing settings for DFT calculations, potentially including range-separated hybrid functionals.

```orca
```{literalinclude} ../../orca_working_input/C06S02_261.inp
:language: orca
```
```

--------------------------------

### DLPNO-CCSD/C-PCM Input Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/solvationmodels.md.txt

Example input file for a DLPNO-CCSD calculation with C-PCM solvent effects using the PTES scheme.

```orca
! DLPNO-CCSD cc-pVTZ cc-PVTZ/C TightSCF CPCM(Water)

* xyz 0 1
O  -0.00000018976103    0.00606010894837    0.00000000004527
H   0.76098169249695   -0.58891312953082   -0.00000000000022
H  -0.76098151333900   -0.58891299029372   -0.00000000000022
*
```

--------------------------------

### MCD Calculation Input Examples

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/mcd.md.txt

Example input files for running MCD calculations in MRCI, CAS, ROCIS, and STEOM modules.

```orca
! MRCI ...
%mcd
  ...
end
* xyz 0 1
  ...
*
```

```orca
! CAS ...
%mcd
  NewMCD True
  ...
end
* xyz 0 1
  ...
*
```

```orca
! ROCIS ...
%mcd
  NewMCD True
  ...
end
* xyz 0 1
  ...
*
```

```orca
! STEOM-CCSD ...
%mcd
  ...
end
* xyz 0 1
  ...
*
```

--------------------------------

### Set Custom Install Path with ORCA Installer

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/faq.md.txt

Example of how to use the '-p' option with the ORCA installer to specify a custom installation directory. The options must follow a double dash.

```bash
./orca_6_0_0_linux_x86-64_shared_openmpi416.run -- -p /my/home/orca/dir
```

--------------------------------

### Demonstrate GoTo Command

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound_examples.md.txt

A brief example demonstrating the usage of the *GoTo* command in ORCA Compound.

```orca
%base_section

# Example of the GoTo command

# This script demonstrates the usage of the GoTo command in ORCA Compound.

# The GoTo command is used to jump to a specific section of the input file.

# In this example, the GoTo command is used to jump to the "section2" section.

%method
  HF def2-SV(P)
%end

%coords
  Angstrom

  C   0.000000   0.000000   0.000000

%end

%section1
  # This is section 1
  GoTo section2
%end

%section2
  # This is section 2
  Print "Hello, World!"
%end

%run
  Jobname goTo_Example
  NProcs 4
%end

```

--------------------------------

### View CI Settings Output

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/energygradients.md.txt

Example output detailing CI strategy, configuration counts, and convergence thresholds.

```text
CI-STEP:
	CI strategy                         ... General CI
	Number of multiplicity blocks       ...    1
	BLOCK  1 WEIGHT=   1.0000
	Multiplicity                      ...    1
	#(Configurations)                 ... 8455
	#(CSFs)                           ... 13300
	#(Roots)                          ...    1
	ROOT=0 WEIGHT=    1.000000
	
	PrintLevel                        ...    1
	N(GuessMat)                       ...       512
	MaxDim(CI)                       ...        10
	MaxIter(CI)                       ...        64
	Energy Tolerance CI               ...  1.00e-13
	Residual Tolerance CI             ...  1.00e-13
	Shift(CI)                         ...  1.00e-04
	...
```

--------------------------------

### GAMESS-US Basis Set Format Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/basisset.md.txt

This is an example of the basis set format compatible with GAMESS-US, used for defining atomic orbitals and their exponents. Lines starting with '!' or '#' are comments.

```basis
!                         lines in the beginning with '!' or '#' are comments
! BASIS="3-21GSP"
!Elements                             References                                
!--------                             ----------                                
! H - Ne: A.V. Mitin, G. Hirsch, R. J. Buenker, Chem. Phys. Lett. 259, 151 (1996)
! Na - Ar: A.V. Mitin, G. Hirsch, R. J. Buenker, J. Comp. Chem. 18, 1200 (1997). 
!
$DATA        ! Optional
Hydrogen     ! (3s) -> [2s]      Element symbols are also recognized
 S   2
  1           4.50036231         0.15631167
  2           0.68128924         0.90466909
 S   1
  1           0.15137639         1.00000000
CARBON       ! (6s,3p) -> [3s,2p]                                
 S   3
  1         499.24042249         0.03330322
  2          75.25419194         0.23617745
  3          16.86538669         0.81336259
 L   2       ! L shells are a s and a p shell with identical exponents
  1           0.89739483         0.24008573         0.46214684
  2           0.21746772         0.81603757         0.66529098
 L   1
  1           4.52660451         1.00000000         1.00000000
$END         ! Optional
```

--------------------------------

### ReadProperty Command Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound.md.txt

Demonstrates reading calculated values from a property file.

```orca
{literalinclude} ../../orca_working_input/compound_example_properertyFile_readProperty.inp
:language: orca
```

--------------------------------

### View ICE-CI Output

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/energygradients.md.txt

Example output showing ICE-CI configuration settings and macroiteration progress.

```text
ICE-CI:
	General Strategy                 ... CONFIGURATIONS (all CSFs to a given CFG, spin adapted)
	Max. no of macroiterations       ...   12
	Variational selection threshold  ... -1.000e-07
	negative! => TVar will be set to 1.000e-07*Tgen=1.000e-11
	Generator selection threshold    ... 1.000e-04
	Excitation level                 ... 2
	Selection on initial CSF list    ... YES
	Selection on later CSFs lists    ... YES
	
	...
	
******************************
*  ICECI MACROITERATION   3  *
******************************
```

--------------------------------

### ORCA Docker Initialization Details

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/docker.md.txt

This output section provides details about the Docker's initialization, including grid settings, worker population, and the minimization algorithm used for evolving structures.

```text
Starting Docker
---------------
Guest structure                      .... structure number 1
Guest charge and multiplicity        .... (0 , 1)
Final charge and multiplicity        .... (0 , 1)
PES used during evolution            .... GFN2-XTB
Setting random seed                  .... done
Creating spatial grid                
   Grid Max Dimension                5.50 Angs
   Angular Grid Step                 32.73 degrees
   Cartesian Grid Step               0.50 Angs
   Points per Dimension              11 points
Initializing workers
   Population Density                0.50 worker/Ang^2
   Population Size                   57
Evolving structures
   Minimization Algorithm            mutant particle swarm
   Min, Max Iterations               (3 , 10)

```

--------------------------------

### ReadMOs Command Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound.md.txt

Demonstrates reading molecular orbitals from a specified previous step.

```orca
{literalinclude} ../../orca_working_input/compound_example_readMOs.inp
:language: orca
```

--------------------------------

### Perform a two-step optimization with semi-empirical Hessian

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/optimizations.md.txt

Example input file for a two-step optimization process starting with a semi-empirical Hessian.

```orca
%geom
 AddExtraBonds true         # switch on/off assigning bonds to atom pairs that are 
                            #  connected by more than <Max_Length> bonds and are less  
                            #  than <MaxDist> Ang. apart (default true)
 AddExtraBonds_MaxLength 10 # cutoff for number of bonds connecting the two
                            #  atoms (default 10)
 AddExtraBonds_MaxDist 5    # cutoff for distance between two atoms (default 5 Ang.)
end
```

--------------------------------

### Geometry Optimization with RI Method

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/optimizations.md.txt

This example demonstrates a geometry optimization using the RI approximation. The BP functional is recommended for this setup.

```orca
! BP/def2-SVP

%method
   RI True
end

%pal
 nprocs 4
end

* xyz 0 1
 C 0.000000 0.000000 0.000000
 C 1.313000 0.000000 0.000000
 H 1.680000 0.935000 0.000000
 H 1.680000 -0.935000 0.000000
* end
```

--------------------------------

### Basic Molecular Dynamics Simulation Setup

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/moldyn.md.txt

This snippet shows a basic ORCA input for activating and configuring a molecular dynamics simulation, including defining the simulation parameters and the initial molecular geometry.

```orca
! MD BLYP D3 def2-SVP
%md
  Timestep 0.5_fs # This is a comment
  Initvel 350_K
  Thermostat NHC 350_K Timecon 10.0_fs
  Dump Position Stride 1 Filename "trajectory.xyz"
  Run 200
end
* xyz 0 1
O         -4.54021        0.78439        0.09307
H         -3.64059        0.38224       -0.01432
H         -4.63463        1.39665       -0.67880
*

```

--------------------------------

### Compound Script Loop Example

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/compound.md.txt

This snippet demonstrates the start of a loop within a compound script, iterating over a defined number of steps for calculations.

```orca
# Loop over the number of steps

```

--------------------------------

### Get Bond Distance Between Atoms

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound.md.txt

Calculates the distance between two specified atoms in a geometry object, returning the result in Bohrs. Atom indices start from 0.

```orca
res = geom.GetBondDistance(atomA, atomB)
```

--------------------------------

### SA-CASSCF Calculation Setup

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/casscf.md.txt

Example input for a SA-CASSCF calculation, including basis set, parallelization, and CASSCF specific keywords like number of electrons, orbitals, and roots.

```orca
! def2-SVP def2-SVP/C ZORA CPCM PAL8
! NormalPrint
! NoLoewdin NoMulliken

%casscf
nel 5
norb 5
nroots 1, 24
mult 6, 4
#rel
#dosoc true
#end
end


* xyz -3 6
Fe      0       0       0
Cl      2.40    0       0
Cl      -2.40   0       0
Cl      0       2.40    0
Cl      0       -2.40   0
Cl      0       0       2.40
Cl      0       0       -2.40
*

```

--------------------------------

### Example: Continue Command

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound.md.txt

Demonstrates the use of the continue command within a loop structure.

```orca
{literalinclude} ../../orca_working_input/ORCA_Test_1797.inp
:language: orca
```

--------------------------------

### Example Configuration File (Partial Export)

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/orca_2json.md.txt

This configuration file disables molecular coefficients and basis set information, exporting only specified integrals and densities.

```orca
{
	"MOCoefficients": false,
	"Basisset": true,
	"1elPropertyIntegrals": ["dipole", "quadrupole", "velocity", "printLinMom", "angular_momentum", "higherMoment"],
	"1elPropertyRelIntegrals": ["dipole", "quadrupole", "angular_momentum"],
	"1elIntegrals": ["H", "S", "T", "V", "HMO"],
	"1elIntegralsRel": ["H", "S", "T", "V", "HMO"],
	"Vaux": false,
	"AuxBasisType": "AuxC"
	"FullTrafo": false,
	"OrbWin": [0,0,0,0,0,0,0,0].
	"2elIntegrals": [ "MO_IJKL", "RI_IAV", "RI_IJKL"],
	"2elNonRedIntegrals": false,
	"2elNonRedRIIntegrals": false,
	"MullikenCharge": false,
	"LoewdinCharge": false,
	"Densities": ["all"],   <--- here you specify the names like "scfp" or "scfr" or all
	"JSONFormats": ["json", "bson"]
}
```

--------------------------------

### NEB-TS Calculation with XTB

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/optimizations.md.txt

Example of an NEB-TS run for intramolecular proton transfer using the XTB method. Requires the starting structure in the XYZ block and the final structure in 'final.xyz'.

```orca
!XTB NEB-TS
%neb
 neb_end_xyzfile "final.xyz"
end

*xyz 0 1
C      0.416168     0.038758    -0.014077
C      0.041816     0.011798     1.439610
O      1.524458     0.176600    -0.453888
O     -0.654209    -0.127881    -0.803857
H     -0.391037    -0.126036    -1.737478
H     -0.913438     0.507022     1.585301
H     -0.057787    -1.026455     1.750845
H      0.819515     0.485425     2.030252
*
```

--------------------------------

### Example: MakeReferenceFromDir

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/compound.md.txt

Creates a JSON reference file from xyz files in a specified directory.

```orca
{literalinclude} ../../orca_working_input/compound_example_dataset_makeReferenceFromDir.inp
:language: orca
```

--------------------------------

### Run GOAT-EXPLORE for Au8 Nanoparticle

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/GOAT.md.txt

Use the !XTB1 GOAT-EXPLORE PAL16 options to find the minimum energy conformer of an Au8 nanoparticle. This example starts from a random agglomeration of gold atoms.

```orca
!XTB1 GOAT-EXPLORE PAL16 #XTB version 6.4.0
%GOAT NWORKERS 16 END
* xyz 0 1
Au        -1.39858        2.62611       -0.79278
Au        -2.50552       -0.07122        0.67538
Au        -0.52174       -2.57892       -0.02415
Au         0.78881        0.39733        0.21816
Au         1.21116        1.90621       -2.64617
Au        -1.19205       -0.30099       -2.30429
Au        -0.33808       -1.07129        2.90822
Au        -0.85565        2.15342        2.41956
*

```

--------------------------------

### Basic ORCA Input File Structure

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/structure.md.txt

This example demonstrates a simple ORCA input file containing a keyword line, an input block for SCF convergence, and coordinate specifications.

```orca
! HF def2-TZVP

%scf
   convergence tight
end

* xyz 0 1
C  0.0  0.0  0.0
O  0.0  0.0  1.13
*
```

--------------------------------

### Example ORCA Input for Specific TDDFT Roots (CIS)

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/orca_2json.md.txt

This JSON configuration requests information for specific TDDFT roots in CIS calculations. Use CISNRoots to get information for all roots.

```json
{
  "input": {
    "CISROOT": [1, 3, 5]
  }
}
```

--------------------------------

### DeltaSCF Input for Water Molecule Ionization

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/deltascf.md.txt

Example input for a DeltaSCF calculation to ionize the 1s electron of a water molecule (MO 0). This setup uses PBE0, DEF2-TZVP, NODIIS, and UHF.

```orca
!PBE0 DEF2-TZVP DELTASCF NODIIS UHF
%SCF IONIZEALPHA 0 END
* xyz 0 1
  O      2.127880   -0.361920    0.104770
  H      3.117210   -0.387460    0.070360
  H      1.838520   -0.926280   -0.655730
*
```

--------------------------------

### Configure ICE-CI for Ground State

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/iceci.md.txt

Example configuration for a ground state calculation using ICE-CI with specific convergence thresholds and algorithm settings.

```text
%ice
  nel     8
  norb    23
  nroots   1
  tvar 1e-11
  tgen 1e-04
  etol 1e-06

  # selection
  SelStart false 
  SelIter  false 
  # algorithm details
  useivos   false
  integrals exact
  cimaxdim     5 #Davidson expansion space = MaxDim * NRoots
  cimode        3

  # spatial sym (buggy)
  irrep 0
  # startup (optional)
  refs { 2 1 0 1 0 2 1 0 1 } 
       end
end
```

--------------------------------

### Start fic-MRCC with %autoci

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/autoci.md.txt

This example shows how to initiate a fic-MRCC calculation by specifying the 'citype fic-mrcc' within the %autoci block. It computes the singlet ground state energy of four hydrogen atoms.

```orca
! cc-pVTZ Bohrs  # it is possible to add the `fic-MRCC' keyword here
                 # and omit the %autoci block below

%maxcore 10000

%casscf
  nel 2
  norb 2
  mult 1
  nroots 1
end

%autoci  # CAS settings are automatically copied from the CASSCF block!
  citype fic-mrcc
end

* int 0 1
  H 0 0 0 0.0  0.0 0.0
  H 1 0 0 2.0  0.0 0.0
  H 2 1 0 2.0 90.0 0.0
  H 1 2 3 2.0 90.0 0.0
*
```

--------------------------------

### ORCA Input for Double-Hybrid DFT

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/energygradients.md.txt

Example ORCA input file demonstrating the use of a double-hybrid functional (wB97M(2)) with pre-converged orbitals. This setup is suitable for single-point energy calculations when orbitals are obtained with a different functional.

```orca
%D3S6        0.61
  D3S8        0
  D3A1        0    # for all DSD-DFs
  D3A2        6.2
end
%mp2
  DoSCS       True
  RI          True
  PS          0.46
  PT          0.09
end

```

--------------------------------

### Example ORCA Input for 2-Electron RI with Orbital Window

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/orca_2json.md.txt

This example demonstrates setting the orbital window using the OrbWin keyword in an ORCA input file for 2-electron RI calculations.

```json
{
  "input": {
    "OrbWin": [
      [0, 8, 9, 15],
      [0, 12, 13, 30, 0, 12, 13, 30]
    ]
  }
}
```

--------------------------------

### Configure DIIS Parameters in ORCA

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/scfconv.md.txt

Control the Direct Inversion in Iterative Subspace (DIIS) procedure using various parameters. These settings influence convergence speed and stability. The 'DIIS Start' parameter controls when DIIS is initiated, 'DIISMaxIt' sets a maximum iteration limit for starting DIIS, and 'DIISMaxEq' defines the number of old Fock matrices to store. 'DIISBFac' biases the SCF cycle towards lower energies, and 'DIISMaxC' limits the extrapolation. The example also shows a more concise way to set multiple DIIS parameters.

```orca
%scf
  # control of the DIIS procedure
  CNVDIIS     true  # default: true
  DIISStart   0.1   # default: 0.2
  DIISMaxIt   5     # default: 12
  DIISMaxEq   7     # default: 5
  DIISBFac    1.2   # default: 1.05
  DIISMaxC    15.0  # default: 10.0
  # more convenient:
  DIIS Start 0.1  MaxIt 5  MaxEq 7  BFac 1.2  MaxC 15.0  end
end
```

--------------------------------

### ORCA Installer Options

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/faq.md.txt

These are command-line options for the ORCA installer, used to customize the installation path or to only extract files.

```bash
  -i        : Set a different install path interactively
  -p <path> : Set a different install path
  -x        : Just extract
```

--------------------------------

### Example Input File with Orbital Selection

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/mreom.md.txt

An example ORCA input file demonstrating the use of the orbital selection procedure for ferrocene calculation. The details of the selection process are printed in the output under the 'ORBITAL SELECTION' heading.

```orca
include ../../orca_working_input/C06S23_496.inp
```

--------------------------------

### Run ORCA Installer (Linux/MacOS)

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/faq.md.txt

Execute the ORCA installer script after making it executable. This command initiates the installation process.

```bash
./orca_6_0_0_linux_x86-64_shared_openmpi416.run
```

--------------------------------

### Configure FMM-QMMM Parameters

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/fmm.md.txt

Shows how to enable FMM-QMMM via the keyword line or detailed parameter configuration in the %method block.

```orca
#keyword line
! FMM-QMMM

#OR through method block

%method
  DOFMMQMMM             True  #turn ON the use of the FMM   
  USEFMMQMMM            True  #turn ON the use of the FMM  
  ###parameters:
  FMMQMMM_DoVFMM        True  #Use the Very Fast Multipole Method 
  FMMQMMM_MAM             20  #Maximum Angular Momentum
  FMMQMMM_Levels           0  #Number of levels set to 0, will be set automatically by box dim 
  FMMQMMM_BoxDimInp      9.0  #Higher boundary to set up the dimension (in Bohr!)
  FMMQMMM_DoBoxDimOpt   True  #Optimize the box dimension
end
```

--------------------------------

### Basic Command Syntax with Optional Arguments

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/detailed/moldyn.md.txt

Illustrates the basic structure of a command with non-optional and optional arguments. Ensure optional arguments are provided in the correct order without gaps.

```orca
%md
  Command Arg1 Arg2 Arg3                  # fine
  Command Arg1, Arg2, Arg3                # fine
  Command Arg1 Arg2 Arg3 Optarg1          # fine
  Command Arg1 Arg2 Arg3 Optarg1 Optarg2  # fine
  Command Arg1 Arg2 Arg3 Optarg2          # will not work
end
```

--------------------------------

### Example MOL-CRYSTAL-QMMM Input

Source: https://www.faccts.de/docs/orca/6.0/manual/_sources/contents/typical/qmmm.md.txt

An example input file for a MOL-CRYSTAL-QMMM calculation, specifying the calculation method, optimization, frequency, and QMMM parameters including QM atom ranges.

```orca
! MOL-CRYSTAL-QMMM
! PBE def2-SVP Opt NumFreq
%qmmm
 NUnitCellAtoms 13
 QMAtoms {221:233} end                   
 ActiveAtoms {221:233} end  
end
*xyzfile 0 1 Ala_SC.xyz
```
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