The SMILES generated from DFT-NBO data are based on high quality (and expensive) calculations of both ligand charge and bonding pattern. In contrast, using an extended Hückel calculation for the charge guess and a simple distance cutoff for the bonding pattern can be expected to make wrong predictions frequently. Thus, when working with extended Hückel calculations we apply a custom procedure to catch and possibly correct these wrong predictions. The procedure going from xyz coordinates and overall charge (Q) to an RDKit mol object is outlined in Figure and is as follows.