QM9 data set is one of the widely used data sets, a collection of molecular structures and properties for 134,000 small organic molecules. QM9 targets neutral organic molecules containing up to nine non-hydrogen atoms (C, N, O, and F). This selection corresponds to the GDB-9 subset of the larger GDB-17 database. While ensuring a manageable size, it captures a significant portion of organic chemical space. Notably, the data set incorporates relevant biomolecules like amino acids (glycine, alanine) and nucleobases (cytosine, uracil, thymine), alongside pharmaceutically important building blocks (pyruvic acid, piperazine, hydroxyurea). Among the 134,000 molecules, 621 distinct chemical formulas (stoichiometries) are present, with C 7 H 10 O 2 being the most abundant, containing 6,095 constitutional isomers.