As stated in Sections 15.3 and 15.5, the canonical MOs of a molecule can be chosen so that each one transforms according to one of the symmetry species of the molecule when the molecular symmetry operators are applied. The same is true of the normal-mode vibrations. For example, when each of the four symmetry operators of H2O is applied to the ω1 vibration in Fig. 15.16, the vibration displacement vectors end up looking unchanged. This normal mode therefore belongs to the totally symmetric symmetry species a1. Give the symmetry species of the other two normal modes in Fig. 15.16. Take the axes as in Fig. 15.1

y H2 ,