Talk:Mod:littleliana3

Introduction No general introduction.

Cope rearrangement Some conformers were successfully identified. Why did you check there were no imaginary frequency? What do you conclude from that? Be careful: energies calculated with different methods (eg. HF and DFT) cannot be compared. Chair and Boat structures successfully identified with the different methods proposed. IRC calculation successfully done and interpreted. Good conclusion about the preferred mechanism.

Diels-Alder Why is the interaction between the HOMO of butadiene and the LUMO of ethene favourable (and vice versa), because of correct overlap (Woodward-Hoffmann rules). This rationalizes why [4+2] is thermally allowed but [2+2] is photochemically allowed. “Since the Endo TS requires less energy of activation, thus it has a smaller imaginary frequency than that of the exo TS.” The frequency is a measure of the curvature of the PES for infinitesimal displacements along the given nuclear coordinate, it does not give information on the height of the barrier.