exogibbs 0.3.9

Differentiable Thermochemical Equilibrium Solver for Exoplanet Atmospheres

ExoGibbs

Differentiable Thermochemical Equilibrium, powered by JAX.

The optimization scheme is based on the Lagrange multiplier, similar to NASA/CEA algorithm. The terminology follows Smith and Missen, Chemical Reaction Equilibrium Analysis (1983, Wiley-Interscience).

Basic Use

from jax import config
config.update("jax_enable_x64", True)

from exogibbs.presets.ykb4 import chemsetup
from exogibbs.api.equilibrium import equilibrium_profile, EquilibriumOptions

# chemical setup
chem = chemsetup()

# Thermodynamic conditions
opts = EquilibriumOptions(epsilon_crit=1e-15, max_iter=1000)

res = equilibrium_profile(
    chem,
    temperature_profile,
    pressure_profile,
    chem.element_vector_reference,
    Pref=1.0,
    options=opts,
)
nk_result = res.x #mixing ratio

presets

• ykb4: number of species: 160 elements: 12
• fastchem: number of species: 523 elements: 28

ExoGibbs is designed to plug into ExoJAX and enable gradient-based equilibrium retrievals. It is still in a beta stage, so please use it at your own risk.

This package bundles logK data from FastChem in fastchem presets, which is distributed under the GNU General Public License v3 (GPLv3). Accordingly, ExoGibbs is also distributed under the GPLv3 license.