ExoMol employs a combination of empirical and ab initio methods to compute comprehensive line lists of spectroscopic transitions for key molecules in extrasolar planetary atmospheres. The data can also be utilised in industrial and other astrophysical spectral studies.

Each molecule considered presents its own challenges and ExoMol relies on the development of custom programs and the use of state of the art computing to tackle the more complex problems.

Recently a hot line list for CH4, YT10to10, has been calculated using DiRAC@Darwin and DiRAC@COSMOS HPC (High Performance Computing) clusters and a specially adapted version of variational program TROVE.

The line lists can be very large, the new CH4 line list contains nearly 10 billion transitions. The size of the line lists is such that constructing a single model may require the consideration of several billion lines. Thus to make the data more accessible to astronomers ExoMol also computes absorption cross-sections. A set of cross-sections is a line list for a single temperature and pressure binned to a lower resolution.

Presented is a summary of the ExoMol project and recent results.