Thermochemistry Analysis

CHEMSMART provides thermochemistry analysis capabilities for computing thermodynamic properties from Gaussian and ORCA output files.

Thermochemistry Analysis Jobs

The thermochemistry command parses output files and calculates thermochemical properties including enthalpy, entropy, and Gibbs free energy.

When processing a directory, use -p/--program when chemsmart needs to identify Gaussian versus ORCA output from the file content, and use -t/--filetype when you only want to filter by filename suffix such as .log or .out.

Usage

chemsmart run thermochemistry [-d path/to/directory] [-p gaussian|orca] [-t filetype] [-f filename(s)]
                              [-csg s_freq_cutoff] [-cst s_freq_cutoff]
                              [-ch h_freq_cutoff] [-c concentration] [-P pressure] [--weighted | --no-weighted]
                              [-T temperature] [-a alpha] [-u hartree|eV|kcal/mol|kJ/mol]
                              [-o outfile.dat] [-O] [-i] [-S|-R]

Options

Input Options:

Option	Type	Description
`-d, --directory`	string	Directory for batch processing (mutually exclusive with `-f`)
`-p, --program`	string	Program that produced the output files: `gaussian` or `orca`. Use this when parsing depends on program identity, for example to distinguish Gaussian and ORCA outputs that may share extensions.
`-t, --filetype`	string	File extension to filter when using `-d` (e.g. `log`, `out`). Use this when selection is purely suffix-based, regardless of which program generated the files.
`-f, --filenames`	string	Specific file(s) to analyze (repeatable, mutually exclusive with `-d`)

Quasi-RRHO Corrections:

Option	Type	Description
`-csg, --cutoff-entropy-grimme`	float	Grimme’s quasi-RRHO entropy cutoff frequency (cm⁻¹)
`-cst, --cutoff-entropy-truhlar`	float	Truhlar’s quasi-RRHO entropy cutoff frequency (cm⁻¹)
`-ch, --cutoff-enthalpy`	float	Head-Gordon’s quasi-RRHO enthalpy cutoff frequency (cm⁻¹)

Note

-csg and -cst are mutually exclusive. If neither is specified, no quasi-RRHO entropy correction is applied.

Thermodynamic Conditions:

Option	Type	Description
`-c, --concentration`	float	Solution concentration in mol/L (mutually exclusive with -P)
`-P, --pressure`	float	Gas-phase pressure in atm (default: 1.0)
`-w, --weighted, --no-weighted`	bool	Toggle between natural abundance weighted masses (`--weighted`) and most abundant isotope masses (`--no-weighted`). Default: `--weighted`.
`-T, --temperature`	float	Temperature in Kelvin (required)
`-a, --alpha`	int	Interpolator exponent (default: 4)

Output Options:

Option	Type	Description
`-u, --energy-units`	string	Units: hartree, eV, kcal/mol, kJ/mol (default: hartree)
`-o, --outputfile`	string	Output filename (default: <basename>.dat)
`-O, --overwrite`	bool	Overwrite existing output files
`-i, --check-imaginary-frequencies`	bool	Check for imaginary frequencies
`-S/-R, --skip-completed/--no-skip-completed`	bool	Skip or rerun completed jobs

Examples

Single file analysis:

chemsmart run thermochemistry -T 298.15 -f water_opt.out

Output:

Structure                        E        ZPE          H       T.S        G(T)
================================================================================
water_opt               -76.323311   0.021581  -76.297951   0.021430  -76.319381

Multiple files:

chemsmart run thermochemistry -T 298.15 -f he_gaussian.log -f he_orca.out

Batch processing:

chemsmart run thermochemistry -T 298.15 -d . -p gaussian -o thermo.dat

Select files by extension only:

chemsmart run thermochemistry -T 298.15 -d . -t log -o thermo_logs.dat

Batch processing with custom pressure:

chemsmart run thermochemistry -T 298.15 -P 2.5 -d . -p gaussian -o thermo.dat

Note

Both -p (program) and -P (pressure) are case-sensitive options that can be used together. -p specifies the quantum chemistry program that generated the files, while -P specifies the pressure in atm.

Solution phase:

chemsmart run thermochemistry -T 298.15 -f co2.log -c 1.0

With quasi-RRHO corrections:

# Grimme's entropy correction
chemsmart run thermochemistry -T 298.15 -f water_mp2.log -csg 100

# Head-Gordon's enthalpy correction
chemsmart run thermochemistry -T 298.15 -f water_mp2.log -ch 200

# Both corrections
chemsmart run thermochemistry -T 298.15 -f water_mp2.log -cst 40 -ch 100

Boltzmann Weighted Averaging Jobs

The boltzmann subcommand performs Boltzmann-weighted averaging of thermochemical results across multiple conformers.

Usage

chemsmart run thermochemistry [THERMO_OPTIONS] boltzmann [-w gibbs|electronic] [-S|-R]

Options

Option	Type	Description
`-w, --energy-type-for-weighting`	string	Weighting scheme: gibbs or electronic (default: gibbs)
`-S/-R, --skip-completed/--no-skip-completed`	bool	Skip or rerun completed jobs

Examples

Boltzmann averaging of conformers:

chemsmart run thermochemistry -T 298.15 -f conf1.log -f conf2.log boltzmann -w electronic

Output:

Structure                                        E        ZPE          H       T.S        G(T)
================================================================================================
conformer_boltzmann_avg_by_electronic   -2189.631938   0.288732  -2189.312517   0.097016  -2189.409533

Batch directory averaging:

chemsmart run thermochemistry -T 298.15 -d . -p gaussian boltzmann

Results are saved to thermochemistry_job_boltzmann.dat.