Classification of Organic Molecules by Molecular Quantum Numbers

Classifying organic molecules using counts for simple structural features, such as atom, bond and ring types, called molecular quantum numbers (MQNs), defines a universal chemical space for analyzing large molecular databases such as ZINC and GDB. The organization of MQN space is revealed by principal component analysis (PCA), as shown for the GDB-11 database (26.4 million structures, up to 11 atoms of C, N, O, F).