Usage

Command-Line Interface

pyglenn provides a CLI for quick thermochemical lookups.

pyglenn --help

Building the Database (optional)

The database comes pre-built and bundled with the package. You only need to rebuild if:

The database file gets corrupted
You modify the thermo.inp coefficients manually

from pyglenn import ThermoDBBuilder

builder = ThermoDBBuilder('path/to/thermo.inp', 'thermo.db')
builder.connect()
builder.create_tables()
builder.parse_and_load()
builder.close()

Using the Calculator

Simply instantiate with no arguments — the bundled database is used automatically:

from pyglenn import ThermochemicalCalculator

with ThermochemicalCalculator() as calc:
    # Find methane — exact_match=True avoids confusion with
    # species like CH3CHCH4 or C2H4 that contain 'CH4'
    species = calc.get_available_species('CH4', exact_match=True)
    result = calc.calculate_properties(species[0].id, 500.0)
    print(f"Cp  = {result.cp:.3f} J/(mol·K)")
    print(f"H°  = {result.h_relative:.3f} J/mol")
    print(f"S°  = {result.s:.3f} J/(mol·K)")

You can also specify a custom database file:

with ThermochemicalCalculator('custom.db') as calc:
    ...

Error Handling

The calculator raises specific exceptions for common errors:

DatabaseNotConnectedError — database not connected
SpeciesNotFoundError — species not found in database
TemperatureOutOfRangeError — temperature outside valid range
ThermoCalcError — base exception for all calculator errors

Migration from dictionaries (v0.1.x)

As of v0.2.0, public methods return typed dataclasses instead of plain dictionaries. Convert old code by replacing result['key'] with result.key:

# v0.1.x (dict)
props = calc.calculate_properties(species_id, 500.0)
cp = props['cp']
name = props['species_name']

# v0.2.0 (dataclass)
props = calc.calculate_properties(species_id, 500.0)
cp = props.cp
name = props.species_name

To recover the previous dictionary shape (for JSON or legacy consumers), use dataclasses.asdict() or the to_dict() method:

from dataclasses import asdict

payload = asdict(calc.calculate_properties(species_id, 500.0))

The typed models are ThermoProperties, SpeciesInfo, SpeciesData, IntervalData, NASACoefficients and DatabaseStats.