(A) BZP and CBC structures. The atom numbering used in this work is shown. (B) Comparison of BZP and CBC QM- and MM-optimized structures and dipoles after parameterization. QM-optimized structure is in orange. Atoms in MM-optimized structure are CPK-colored: green carbons, red oxygens, blue nitrogens, white hydrogens, yellow sulfurs. Arrows show dipole orientation, in orange and green for QM and MM, respectively.