In order to discriminate molecules that share their molecular formula (i.e. isomers), we assigned SMILES for each of the filtered amino acid-compatible structures with OpenBabel 64 and sanitize them with RDKit. Necessary to assign polarizabilities, the atom types of each structure where determined using a decision tree (see Figure ), analyzing elements, bonds and distances with neighboring atoms, following the definitions of Litman et. al. After the classification procedure, we categorized the atoms within our data set into three types of hydrogen (Har, Hnonpol, Hpolar), five types of carbon (Car, Cnonpol, Cpolar, Csp, Cvac), four types of nitrogen (Nar, Nnonpol, Npolar, Nsp), and three types of oxygen (Ononpol, Osp2c, Ohacid). Cvac represents carbon atoms for which the atom type could not be assigned to any other carbon type.