The four resulting systems from the procedure described above were clusters of molecules that had atoms each. Constrained optimizations were performed on the structures to determine other minima and first order saddle-points in between them. Transition state optimizations were done with the synchronous transit-guided quasi-Newton method at the respective basis sets mentioned above, followed by vibrational frequency calculations to establish that structures are true saddle points. All minima were fully optimized and analyzed for harmonic vibrational frequencies and zero-point energies. Optimization calculations yield stationary points that are internal energy minima along a potential energy surface (PES), which is a hypothetical surface where vibrations are absent. However, even in the ground state, a chemical system would have a ground state energy or zero-point energy. Hence, internal energies need to be corrected and form another surface that is elevated in energy from the PES, or a zero-point energy corrected PES. While the two surfaces might have similar topologies, this may not always be the case particularly in the case of shallow potential energy wells.