Gaussian 09 Job Types
The route section of a Gaussian 09 input file specifies the type of calculation to be performed. There are three key components to this specification:
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The job type
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The method
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The basis set
The following table lists the job types available in Gaussian 09:
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SP: Single point energy.
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Opt: Geometry optimization.
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Freq: Frequency and thermochemical analysis.
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IRC: Reaction path following.
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IRCMax: Find the maximum energy along a specific reaction path.
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Scan: Potential energy surface scan.
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Polar: Polarizabilities and hyperpolarizabilities.
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ADMP and BOMD: Direct dynamics trajectory calculation.
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Force: Compute forces on the nuclei.
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Stable: Test wavefunction stability.
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Volume: Compute molecular volume.
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Density=Checkpoint Guess=Only: Recompute population analysis only.
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Guess=Only: Print initial guess only; generate fragment-based initial guess.
In general, only one job type keyword should be specified. The exceptions to this rule are:
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Polar and Opt may be combined with Freq. In the latter case, the geometry optimization is automatically followed by a frequency calculation at the optimized structure.
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Opt may be combined with the compound method keywords in order to specify options for the optimization portion of the calculation: e.g., Opt=(TS,ReadFC) CBS-QB3.
When no job type keyword is specified within the route section, the default calculation type is usually a single point energy calculation (SP). However, a route section of the form: method2/basis2 // method1/basis1 may be used to request an optimization calculation (at method1/basis1) followed by a single point energy calculation (at method2/basis2) at the optimized geometry. For example, the following route section requests a B3LYP/6-31G(d) geometry optimization followed by a single point energy calculation using the CCSD/6-31G(d) model chemistry:
# CCSD/6-31G(d)//B3LYP/6-31G(d) Test
In this case, the Opt keyword is optional and is the default. Note that Opt Freq calculations may not use this syntax.
Predicting Molecular Properties
The following table provides a mapping between commonly-desired predicted quantities and the Gaussian 09 keywords that will produce them:
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Antiferromagnetic coupling: Guess=Fragment, Stability
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Atomic charges: Pop
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ΔG of solvation: SCRF=SMD
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Dipole moment: Pop
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Electron affinities: CBS-QB3, CCSD, EPT
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Electron density: cubegen
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Electronic circular dichroism: CIS, TD, EOM, SAC-CI
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Electrostatic potential: cubegen, Prop
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Electrostatic potential-derived charges: Pop=Chelp, ChelpG or MK
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Electronic transition band shape: Freq=FC, Freq=HT
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Polarizabilities/hyperpolarizabilities: Freq, Polar [CPHF=RdFreq], Polar=DCSHG
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High accuracy energies: CBS-QB3, G2, G3, G4, W1U, W1BD
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Hyperfine coupling constants (anisotropic): Prop
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Hyperfine spectra tensors (including g tensors): Freq=(VCD, VibRot [, Anharmonic])
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Ionization potentials: CBS-QB3, CCSD, EPT
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IR and Raman spectra: Freq[=Anharmonic]
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Pre-resonance Raman spectra: Freq CPHF=RdFreq
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Molecular orbitals: Pop=Regular
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Multipole moments: Pop
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NMR shielding and chemical shifts: NMR
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NMR spin-spin coupling constants: NMR=Mixed
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Optical rotations: Polar=OptRot
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Raman optical activity: Freq=ROA, CPHF=RdFreq
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Thermochemical analysis: Freq
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UV/Visible spectra: CIS, ZIndo, TD, EOM, SAC-CI
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Vibration-rotation coupling: Freq=VibRot
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Vibrational circular dichroism: Freq=VCD
Last update: 23 April 2013