PhotochemPy is a photochemical model of rocky planet's atmospheres. Given inputs, like the stellar UV flux, the atmospheric temperature structure, etc., this code will find the steady-state chemical composition of an atmosphere, or evolve atmospheres through time.

PhotochemPy is a Python wrapper to Fortran source code. This makes the code very speedy, but also user-friendly.


To install PhotochemPy, you must have the following installed on your system.

  • Python (>3.6.0) with the numpy package. I suggest using anaconda to install these regardless of your operating system.
  • The GNU compiler collection, version >4.9.4 (includes gfortran, gcc, etc.). If you are using a Mac, I suggest installing it with Homebrew: brew install gcc. For other operating systems follow this GNU installation guide.
  • CMake. On Mac you can install with brew install cmake.

Python Module: After satisfying the requirements, then follow these setups to install PhotochemPy

  • Clone or download the github repository
  • In a terminal, navigate to the folder src/dependencies, and run the shell script
  • Navigate to the root directory of PhotochemPy, then install with python -m pip install .

Fortran source: If you prefer to use the code exclusively in Fortran, that is OK too. An example is provided in the folder examples/fortran_example.


See the examples directory. Also check out this tutorial


PhotochemPy is a distant fork of the Atmos photochemical model, originally developed by Jim Kasting and Kevin Zahnle and further developed by many of their students and colleges.

Contact + Publications

If you have questions email me: [email protected]

Also, if you plan on using PhotochemPy for a publication please email me before you submit anything to a journal, just so we can confirm your planned application of the model is reasonable.