TEA: A Code for Calculating Thermochemical Equilibrium Abundances

TL;DR

TEA is an open-source Python code that calculates thermochemical equilibrium abundances of gaseous molecules using Gibbs free-energy minimization, validated against established methods, and applied to hot-Jupiter exoplanet models.

Contribution

The paper introduces TEA, a new open-source Python tool for calculating molecular abundances in thermochemical equilibrium with higher precision than previous codes.

Findings

TEA accurately reproduces results of previous thermochemical codes.

TEA successfully models molecular abundances in hot-Jupiter atmospheres.

The code is modular, well-documented, and publicly available.

Abstract

We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. (1958) and Eriksson (1971). It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp (1999), the free thermochemical equilibrium code CEA (Chemical Equilibrium with Applications), and the example given by White et al. (1958). Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.