Database

The SQLite database stores NASA polynomial coefficients for each species.

Database Schema

The database contains a species table with these columns:

name — species name (e.g., 'CH4', 'CO2')
phase — phase indicator (G = gas, L = liquid, S = solid)
T_low — minimum valid temperature [K]
T_high — maximum valid temperature [K]
T_mid — midpoint temperature (NASA-7 format)
a1..a7 — high-temperature polynomial coefficients
a8..a14 — low-temperature polynomial coefficients (NASA-7)

NASA Polynomial Format

The coefficients follow the standard NASA polynomial form:

\[\frac{C_p^\circ}{R} = a_1 + a_2 T + a_3 T^2 + a_4 T^3 + a_5 T^4\]

\[\frac{H^\circ}{RT} = a_1 + \frac{a_2}{2}T + \frac{a_3}{3}T^2 + \frac{a_4}{4}T^3 + \frac{a_5}{5}T^4 + \frac{a_6}{T}\]

\[\frac{S^\circ}{R} = a_1 \ln T + a_2 T + \frac{a_3}{2}T^2 + \frac{a_4}{3}T^3 + \frac{a_5}{4}T^4 + a_7\]

Querying the Database

You can query the database directly using ThermoDBQuery:

from pyglenn import ThermoDBQuery

query = ThermoDBQuery('thermo.db')

# List all available species
species = query.list_species()
print(species)

# Get coefficients for a specific species
coefs = query.get_coefficients('CH4')
print(coefs)

query.close()

Universal Gas Constant

The universal gas constant is available as pyglenn.R:

from pyglenn import R

print(f"R = {R} J/(mol·K)")