Electronic Structure Properties & Analyses (Gaussian)

This page covers electronic structure analysis capabilities using Gaussian, including single point calculations, excited state properties, bond analysis, and molecular interaction studies.

Single Point Jobs

Run single point energy calculations on optimized geometries.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] sp [SUBCMD_OPTIONS]

SP Options

Option	Type	Description
`--remove-solvent/--no-remove-solvent`	bool	Disable solvent model (uses project settings by default)
`-sm, --solvent-model`	string	Solvent model (default: project settings)
`-si, --solvent-id`	string	Solvent ID (default: project settings)
`-so, --solvent-options`	string	Additional SCRF options (e.g., `iterative`)

Note

These solvent options can also be provided at the Gaussian group level (before the sp subcommand), in the same way as for opt, td, and all other subcommands. Group-level options take precedence over project settings. See Solvent Options for details.

Basic Usage

Standard single point calculation:

chemsmart sub gaussian -p project -f optimized.log sp

With custom solvent settings:

chemsmart sub gaussian -p project -f molecule.log sp -sm cpcm -si toluene

Gas phase calculation (no solvent):

chemsmart sub gaussian -p project -f ethanol_opt.log -c 0 -m 1 sp --remove-solvent

The output file will be named ethanol_opt_gas_phase.log.

DI-AS Analysis

Run Distortion-Interaction/Activation-Strain (DI-AS) analysis for reaction mechanisms.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] dias [SUBCMD_OPTIONS]

DI-AS Options

Option	Type	Description
`-i, --fragment-indices`	string	Atom indices of one fragment (required)
`-n, --every-n-points`	int	Sample every nth point along IRC (default: 3)
`-s, --solv/--no-solv`	bool	Enable/disable solvent (default: disabled)
`-m, --mode`	string	Analysis mode: `irc` or `ts` (default: irc)
`-c1, --charge-of-fragment1`	int	Charge of fragment 1
`-m1, --multiplicity-of-fragment1`	int	Multiplicity of fragment 1
`-c2, --charge-of-fragment2`	int	Charge of fragment 2
`-m2, --multiplicity-of-fragment2`	int	Multiplicity of fragment 2

Basic Usage

Run DI-AS analysis for atoms 5-17 at every 10th point along an IRC:

chemsmart sub gaussian -p project -f irc.log dias -i 5-17 -n 10

Note

The irc.log file should be the IRC output from the transition state to the reactant side.

RESP Jobs

Run RESP (Restrained Electrostatic Potential) charge fitting calculations.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] resp

Basic Usage

chemsmart sub gaussian -p project -f molecule.xyz resp

Note

This creates an input file with a fixed route for RESP: HF/6-31+G(d) SCF=Tight Pop=MK IOp(6/33=2,6/41=10,6/42=17,6/50=1)

NCI Jobs

Run Non-Covalent Interaction (NCI) analysis for intermolecular interactions.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] nci

Basic Usage

chemsmart sub gaussian -p project -f complex.xyz nci

TD-DFT Jobs

Run time-dependent DFT calculations for excited state properties.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] td [SUBCMD_OPTIONS]

TD-DFT Options

Option	Type	Description
`-s, --states`	string	State type: `singlets`, `triplets`, or `50-50` (default: singlets)
`-r, --root`	int	State of interest (default: 1)
`-n, --nstates`	int	Number of states to solve (default: 3)
`-e, --eqsolv`	string	Equilibrium or non-equilibrium PCM solvation

Basic Usage

Standard TD-DFT calculation:

chemsmart sub gaussian -p project -f molecule.xyz td

Calculate triplet states:

chemsmart sub gaussian -p project -f molecule.xyz td -s triplets -n 5

Calculate 50-50 singlet-triplet mix:

chemsmart sub gaussian -p project -f molecule.xyz td -s 50-50 -n 4

Solvated TD-DFT

Solvent options are given at the Gaussian group level (before td). See Solvent Options for the full option reference.

Gas phase TD-DFT (project default):

chemsmart sub gaussian -p project -f molecule.xyz -c 0 -m 1 -a no_solv_td td

Solvated TD-DFT with SMD/water:

chemsmart sub gaussian -p project -f molecule.xyz -c 0 -m 1 -sm smd -si water -a solv_td td

With the iterative SCRF solver:

chemsmart sub gaussian -p project -f molecule.xyz -c 0 -m 1 -sm smd -si water -so iterative -a solv_td td

The solvated example produces a route line of the form:

cam-b3lyp def2svp scrf=(smd,solvent=water,iterative) TD(singlets,nstates=3,root=1)

WBI Jobs

Run Wiberg Bond Index (WBI) calculations for bond analysis.

chemsmart sub [OPTIONS] gaussian [GAUSSIAN_OPTIONS] wbi

Basic Usage

chemsmart sub gaussian -p project -f opt.log wbi

This adds the keyword pop=nboread for NBO3.1 software analysis.