Gaussian Documentation

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### ADMP Input File Example

Source: https://gaussian.com/admp

A sample input file for calculating the dissociation trajectory of H2CO starting from the transition state.

```text
# B3LYP/6-31G(d) ADMP Geom=Crowd

Dissociation of H2CO → H2 + CO

0 1
C
O 1 r1
H 1 r2 2 a
H 1 r3 3 b 2 180.

r1 1.15275608
r2 1.74415774
r3 1.09413376
a 114.81897892
b 49.08562961
```

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

### BOMD Input Configuration Example

Source: https://gaussian.com/bomd

Example of a BOMD input file for the dissociation of H2CO into H2 and CO.

```text
# HF/3-21G BOMD(Phase=(1,3),RTemp=300,NSample=1,ReadStop) Geom=Crowd |   
---|---  
|   
HF/3-21G dissociation of H2CO –> H2 + CO |   
|   
0 1 |   
C |   
O 1 r1 |   
H 1 r2 2 a |   
H 1 r3 3 b 2 180. |   
|   
r1 1.15275608 |   
r2 1.74415774 |   
r3 1.09413376 |   
a 114.81897892 |   
b 49.08562961 |   
|   
1 |   
1 1 2 2 |   
13.0 11.0 1.3 2.5 0.0000005 1 1 3 12.8 |   
1 5.145 |   
C O -112.09329898 1.12895435 0.49458169 2.24078955 |   
H H -1.12295984 0.73482237 0.19500473 1.94603924 |   
| Final blank line
```

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

### External Iteration Checkpoint Setup

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Initial checkpoint configuration for the External Iteration approach.

```Gaussian
%oldchk=01-ac
%chk=03-ac-EI
```

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

### ADMP Calculation Parameters Output

Source: https://gaussian.com/admp

Example of the parameter summary displayed at the beginning of an ADMP calculation.

```text
 TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ
 --------------------------------------------------------------------
 INPUT DATA FOR L121
 --------------------------------------------------------------------

 General parameters:
 Maximum Steps                =      50
 Random Number Generator Seed =  398465
 Time Step                    =  0.10000 femtosec
 Ficticious electronic mass   =  0.10000 amu
 MW individual basis funct.   = True
 Initial nuclear kin. energy  =  0.10000 hartree
 Initial electr. kin. energy  =  0.00000 hartree
   Initial electr. KE scheme  =  0
 Multitime step - NDtrC       =       1
 Multitime step - NDtrP       =       1
 No Thermostats chosen to control nuclear temperature

 Integration parameters:

 Follow Rxn Path (DVV)        = False
 Constraint Scheme            =      10
 Projection of angular mom.   = True
 Rotate density with nuclei   = True
 --------------------------------------------------------------------
 TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ
```

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

### View Optimized Parameters Output

Source: https://gaussian.com/qst2

Example of the output table displaying optimized parameters for a transition state calculation.

```text
                ---------------------------------
                !     Optimized Parameters      !
                !   (Angstroms and Degrees)     !
-----------------------------------------------------------------
! Name  Definition    Value    Reactant  Product  Deriv Info.   !
-----------------------------------------------------------------
! R1    R(2,1)        1.0836    1.083     1.084   -DE/DX =  0.  !
! R2    R(3,1)        1.4233    1.4047    1.4426  -DE/DX = -0.  !
! R3    R(4,1)        1.4154    1.4347    1.3952  -DE/DX = -0.  !
! ...                                                           !
-----------------------------------------------------------------
```

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

### SCF Energy Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the SCF energy after cycles.

```text
SCF Done:  E(RB3LYP) =  -153.822040461     A.U. after   10 cycles
```

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

### View DFT Model Parameters in Output

Source: https://gaussian.com/dft

Example of the output file format displaying the active DFT parameters and scaling factors.

```text
 IExCor=  402 DFT=T Ex=B+HF Corr=LYP ExCW=0 ScaHFX=  0.200000
 ScaDFX=  0.800000  0.720000  1.000000  0.810000 
```

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

### Excited State Calculation Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the first excited state energy and transition details.

```text
Excited State   1:      Singlet-?Sym    3.2075 eV  386.54 nm  f=0.0014...
      12 -> 13         0.70615
This state for optimization and/or second-order correction.
Total Energy, E(TD-HF/TD-DFT) =  -153.705917055
```

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

### BOMD Initial Parameter Output

Source: https://gaussian.com/bomd

Displays the general and sampling parameters used at the start of a BOMD calculation.

```text
 TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ
 -------------------------------------------------------------------
 INPUT DATA FOR L118
 -------------------------------------------------------------------
 
 General parameters:
 Max. points for each Traj.   =     100
 Total Number of Trajectories =       1
 Random Number Generator Seed =  398465
 Trajectory Step Size         =   0.250 sqrt(amu)*bohr

 Sampling parameters:
 Vib Energy Sampling Option   = Thermal sampling
   Vib Sampling Temperature   =     300.0 K
   Sampling direction         = Forward
 Rot Energy Sampling Option   = Thermal distribution (symmetric top)
   Rot Sampling Temperature   =     300.0 K
 Start point scaling criteria =       1.000D-05 Hartree
 …
 
 Reaction Path  1
 ****************
 Fragment  1    center   1 ( C )   2 ( O )
 Fragment  2    center   3 ( H )   4 ( H )
 Termination criteria:
   The CM distances are larger than 13.000 bohr
   The min atomic distances among fragments are larger than 11.0 bohr
   The max atomic and CM distances in frags are shorter than 1.3 bohr
   The max atomic distances in fragments are shorter than 2.500 bohr
   The change of gradient along CM is less than 5.00D-07 Hartree/bohr
   Distance between atom center 1 ( C ) and 3 ( H ) is GE 12.800 bohr
 
 Morse parameters for diatomic fragments:
            E0            Re            De            Be
 C  O   -112.0932990     1.1289544      0.4945817      2.2407896
 H  H     -1.1229598     0.7348224      0.1950047      1.9460392
---------------------------------------------------------------------
```

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

### Linear Response Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the first excited state energy and wavelength.

```text
Excited State 1: Singlet-A"  4.3767 eV  283.28 nm  f=0.0000  ~~=0.000~~
```

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

### PCM Energy Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the energy after PCM corrections.

```text
After PCM corrections, the energy is  -153.707149257     a.u.
```

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

### Specify Isotopes in Route Section

Source: https://gaussian.com/admp

Example of setting temperature and isotope mass within the route and molecule specification sections.

```text
#T Method/6-31G(d) JobType Temperature=300.0 …

…

0 1
C(Iso=13)
…
```

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

### View DFT Energy Output

Source: https://gaussian.com/dft

Example of the energy output format for a B3LYP calculation in Gaussian.

```text
 SCF Done:  E(RB3LYP) =  -75.3197099428     A.U. after    5 cycles
```

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

### SMD Solvent Definition via PCM Input

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example of manually defining a generic solvent for an SMD calculation by providing the required seven solvent parameters.

```Gaussian Input
# B3LYP/6-31G(d) 5D SCRF(SMD,Solvent=Generic,Read)  
---  
|   
Water in solution with ethanol, defined as generic SMD solvent.  
|   
0 1 |   
O |   
H,1,0.94 |   
H,1,0.94,2,104.5 |   
| Input section for PCM keywords  
Eps=24.852 | ε  
EpsInf=1.852593 | n2  
HbondAcidity=0.37 | α  
HbondBasicity=0.48 | β  
SurfaceTensionAtInterface=31.62 | γ  
CarbonAromaticity=0. | φ  
ElectronegativeHalogenicity=0. | ψ  
| Blank line terminates PCM input
```

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

### PCM Additional Input Configuration

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example of providing additional PCM keywords to tighten convergence and adjust cavity sphere radii.

```Gaussian Input
# B3LYP/6-31G(d) 5D SCRF(Solvent=Ethanol,Read)  
---  
|   
PCM extra input example.  
|   
0 1 |   
molecule specification  
|   
QConv=10 | Input section for PCM keywords  
Alpha=1.1 |   
| Blank line terminates PCM input
```

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

### Gaussian SCRF Job Input

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example of a B3LYP calculation using SCRF with ethanol solvent and non-equilibrium read settings.

```Gaussian
# B3LYP/6-31+G(d,p) SCRF=(Solvent=Ethanol,NonEquilibrium=Read)
  Geom=Check Guess=Read NoSymm

Acetaldehyde: ground state non-equilibrium
at excited state geometry.

0 1
```

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

### BOMD Input Configuration

Source: https://gaussian.com/bomd

Example of a Gaussian input file for a BOMD calculation, including route section and geometry specification.

```Gaussian Input
# HF/3-21G BOMD(Phase=(1,3),RTemp=300,NSample=1,ReadStop) Geom=Crowd |   
---|---  
|   
HF/3-21G dissociation of H2CO --> H2 + CO |   
|   
0 1 |   
C |   
O 1 r1 |   
H 1 r2 2 a |   
H 1 r3 3 b 2 180. |   
|   
r1 1.15275608 |   
r2 1.74415774 |   
r3 1.09413376 |   
a 114.81897892 |   
b 49.08562961 |   
|   
1 |   
1 1 2 2 |   
13.0 11.0 1.3 2.5 0.0000005 1 1 3 12.8 |   
1 5.145 |   
C O -112.09329898 1.12895435 0.49458169 2.24078955 |   
H H -1.12295984 0.73482237 0.19500473 1.94603924 |   
| Final blank line
```

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

### Corrected Linear-Response Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the transition energy and total energy after correction.

```text
PCM Corrected Linear-Response - Non-equilibrium solvation:
Corrected transition energy               =    4.3603          eV
Total energy after correction             = -153.691525835     a.u.
```

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

### View External Iteration SCRF Results

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output for external iteration SCRF calculations, showing the final energy computed by Link 124.

```text
 --------------------------------------------------------------------
 Self-consistent PCM results
 ===========================
                      (a.u.) =     -99.577537  (A)
                      (a.u.) =     -99.584002  (B)
 (Polarized solute)-Solvent               (kcal/mol) =      -4.06  (C)
 --------------------------------------------------------------------
 Partition over spheres:
 Sphere  on Atom  Surface  Charge   GEl     GCav    GDR
    1      H1      15.27  -0.157   -2.36    0.00    0.00
    2      F2      32.58   0.157   -1.70    0.00    0.00
 --------------------------------------------------------------------
 Predicted energy value for external iteration and state-specific SCRF calculations
 After PCM corrections, the energy is  -99.5840023899     a.u. 
 --------------------------------------------------------------------
```

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

### ADMP Trajectory Calculation Input

Source: https://gaussian.com/admp

Sample input file for calculating the dissociation trajectory of H2CO starting from the transition state.

```text
# B3LYP/6-31G(d) ADMP Geom=Crowd

Dissociation of H2CO → H2 + CO

0 1
C
O 1 r1
H 1 r2 2 a
H 1 r3 3 b 2 180.

r1 1.15275608
r2 1.74415774
r3 1.09413376
a 114.81897892
b 49.08562961
```

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

### Display mass-weighted force constant matrix

Source: https://gaussian.com/vib

Example output showing the low-frequency modes of a water molecule at the HF/3-21G* level.

```text
Full mass-weighted force constant matrix:
 Low frequencies ---   -0.0008    0.0003    0.0013   40.6275   59.3808   66.4408
 Low frequencies --- 1799.1892 3809.4604 3943.3536
```

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

### Closed-Shell Singlet Stability Optimization

Source: https://gaussian.com/afc

Performs a stability optimization starting from a closed-shell singlet.

```Gaussian
%oldchk=afc5 
%chk=afc7 
#p rb3lyp/3-21g geom=allcheck stable=opt
```

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

### Gaussian SCF Energy Output

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Example output showing the predicted energy after iterative cycles.

```Gaussian
SCF Done:  E(RB3LYP) =  -153.822031895     A.U. after   10 cycles
```

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

### Stability Analysis Input File

Source: https://gaussian.com/afc

Input file for checking the stability of the wavefunction at the optimized geometry using the checkpoint file from the previous job.

```Gaussian
%oldchk=afc1
%chk=afc2
#p b3lyp/3-21g guess=read geom=check stable=opt             

Mn2O2(NH3)8 High Spin (antiferromagnetic coupling)

0,11
```

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

### Excited State Geometry Optimization and Frequency Input

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Input file for performing a geometry optimization and frequency calculation on the first excited state of acetaldehyde in ethanol.

```Gaussian
# B3LYP/6-31+G(d,p) TD=(NStates=6,Root=1) SCRF=(Solvent=Ethanol)
  Geom=Check Guess=Read Opt=CalcFC Freq NoSymm

Acetaldehyde: excited state opt + freq
Since first excited state is A", the
minimum will break Cs symmetry.

0 1
```

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

### Wavefunction Stability Output Indicators

Source: https://gaussian.com/afc

Example of output lines indicating that an unstable wavefunction has been detected during the stability analysis.

```text
 *********************************************************************** 
Stability analysis using <AA,BB:AA,BB> singles matrix: 
***********************************************************************
```

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

### Vibrational Mode Thermal Sampling Output

Source: https://gaussian.com/bomd

Shows the initial kinetic energies for normal modes at the start of each trajectory step.

```text
 -------------------------------------------------------
          Thermal Sampling of Vibrational Modes
 Mode     Wavenumber     Vib. quant.#  Energy (kcal/mol)
 -------------------------------------------------------
    1     -2212.761                        5.14500
    2       837.330            0           1.19702
    3      1113.182            0           1.59137
    4      1392.476            0           1.99064
    5      2026.859            0           2.89754
    6      3168.689            0           4.52987
-------------------------------------------------------
```

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

### Mulliken Spin Density Output

Source: https://gaussian.com/afc

Displays the Mulliken atomic spin densities from the output file.

```Text
Mulliken atomic spin densities:
              1
     1  Mn   3.931283
     2  O   -0.000000
     3  O   -0.000000
     4  Mn  -3.931283
     5  H    0.005293
     ...
```

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

### Trajectory Step Output Format

Source: https://gaussian.com/admp

Displays the molecular coordinates and velocities at the beginning of each trajectory step.

```text
 Cartesian coordinates:
 I= 1 X= -1.1971360D-01 Y=  0.0000000D+00 Z= -1.0478570D+00 
 I= 2 X= -1.1971360D-01 Y=  0.0000000D+00 Z=  1.1305362D+00
 I= 3 X=  2.8718451D+00 Y=  0.0000000D+00 Z= -2.4313539D+00
 I= 4 X=  4.5350603D-01 Y=  0.0000000D+00 Z= -3.0344227D+00
 MW Cartesian velocity:
 I= 1 X= -4.0368385D+12 Y=  1.4729976D+13 Z=  1.4109897D+14
 I= 2 X=  4.4547606D+13 Y= -6.3068948D+12 Z= -2.2951936D+14
 I= 3 X= -3.0488505D+13 Y=  6.0922004D+12 Z=  1.8527270D+14
 I= 4 X= -1.3305097D+14 Y= -3.1794401D+13 Z=  2.4220839D+14
 Cartesian coordinates after ADCart:
 I= 1 X= -1.1983609D-01 Y=  4.2521779D-04 Z= -1.0437931D+00
 I= 2 X= -1.1859803D-01 Y= -1.5769743D-04 Z=  1.1248052D+00
 I= 3 X=  2.8688210D+00 Y=  6.0685035D-04 Z= -2.4129040D+00
 I= 4 X=  4.4028377D-01 Y= -3.1670730D-03 Z= -3.0103048D+00
 TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ-TRJ
```

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

### Requesting Geometry Optimization and Single Point Energy

Source: https://gaussian.com/capabilities?tabid=1

Use the double-slash syntax to perform a geometry optimization at one level of theory followed by a single-point energy calculation at another.

```Gaussian Input
# CCSD/6-31G(d)//B3LYP/6-31G(d)
```

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

### Initial Velocity Input Format

Source: https://gaussian.com/admp

Format for providing optional initial Cartesian velocities for atoms.

```text
Initial velocity for atom 1: x y z | Optional initial Cartesian velocities  
---|---  
Initial velocity for atom 2: x y z | (ReadVelocity and ReadMWVelocity options)  
… |   
Initial velocity for atom N: x y z |   
… |
```

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

### Excited State Geometry Optimization Checkpoint

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Checkpoint file configuration for retrieving data to perform excited state geometry optimization.

```Gaussian
%oldchk=02-ac
%chk=04-ac
```

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

### External Iteration Input Header

Source: https://gaussian.com/gaussian.com/scrf?tabid=7

Initial lines for the External Iteration approach input file.

```Gaussian
%oldchk=04-ac
%chk=05-ac-EI
```
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