easyCHEM documentation#

Welcome to the easyCHEM documentation. easyCHEM is a Python package for calculating chemical abundances in exoplanet atmospheres, assuming equilibrium chemistry and including condensation. Ancillary outputs are the atmospheric adiabatic temperature gradient and mean molar mass. easyCHEM is a clone of the equilibrium chemistry part of NASA’s CEA code, written from scratch and with numerical stability in mind. In particular, the code implements the equations described in Gordon & McBride (1994) and makes use of LAPACK’s dgesv routine for fast matrix inversion. Since we incorporated the dgesv source code into easyCHEM, users do not require external math libraries.

easyCHEM’s thermodynamic input data is based on the NASA Glenn thermodynamic input database, which can be accessed here. Additional NASA polynomials have been obtained from Lodders & Fegley (2002), Visscher et al. (2010), or were derived from thermodynamic data in the NIST-JANAF database and condensate data listed in Robie et al. (1978). The thermodynamic data of the condensates was extended to low temperatures (60 K) using the method described in Appendix A.2 of Mollière et al. (2017).

To get started with some examples on how to run easyCHEM, see our “easyCHEM tutorial”.

easyCHEM is available under the MIT License, and its base Fortran implementation was described in Mollière et al. (2017). It was benchmarked against the CEA code, leading to identical results. It was also compared to the equilibrium chemistry codes used for the ATMO and Exo-REM atmospheric models, again showing excellent agreement, see Baudino et al. (2017).

Please cite Lei & Mollière (2024) when making use of easyCHEM in your research.

This documentation webpage contains an installation guide, a tutorial, and an API documentation.

easyCHEM documentation

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easyCHEM documentation#

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