Comparison to QM Optimised Structure

The parameters generated by the ATB for each molecule has been used to perform an energy minimisation in vacuum and the resulting structure compared to that obtained after Quantum Mechanical (QM) optimization in implicit solvent (water) at the B3LYP/6-31G* level (≤ 50 atoms) or at the AM1 (or PM3 or HF/STO-3G) level of theory (>50 atoms) using GAMESS-US.

From the distribution of root-mean-square deviation (RMSD) values below, it can be seen that the overall agreement between the QM optimized structures and the energy minimized structures using the ATB parameters is very good which suggests that the geometry of the molecules is well reproduced.