The data is compiled into a database of reference species (henceforth referred to as the "reference database") located within the larger RMG-database, available on GitHub (link provided in SI). The reference database consists of YAML text files, one for each species, that contains information about the species structure (e.g., 3D coordinates and RMG adjacency list representation of the species) along with the heat of formation data from the literature. Some species have data from multiple sources, which are all included in the database, but by default the source with the lowest uncertainty is used for computations.