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A Gas-Grain Chemical Code for astrochemical modelling

UCLCHEM is a gas-grain chemical code for astrochemical modelling that can be used as a stand alone Fortran program or a Python module. It propagates the abundances of chemical species through a network of user-defined reactions according to the physical conditions of the gas.

Included in the repository is MakeRates, a python script to easily produce all the files related to the chemical network required by UCLCHEM. By combining a reaction list from an astrochemistry database such as UMIST with a custom list of reactions, the user can quickly generate a complex network.

UCLCHEM is freely available for use and/or modification for any astrochemical purpose. Please reference our release paper if UCLCHEM is used for work in a publication and feel free to contact us with suggestions, questions or to ask for advice using the code.


Gas-Grain Chemistry

Detailed, consistent treatment of chemistry across the gas phase and both the surface and the bulk of the ice mantles around dust grains.

operating system

Modular Physics

Flexible, interchangeable modules to model all kinds of astrophysical objects such as molecular clouds, protostellar cores and C/J-type shocks.

version control

Active Development

Teams at UCL and Leiden Observatory are working with international collaborators to extend and improve UCLCHEM. Check our blog for recent updates.