There is, however, one aspect of the partition function of the Ts species that is specific to this theory. The qAb. contains all of the usual translational, rotational, vibrational, and electronic partition functions that one would write down, as we did in Chapter 7, for a conventional Ab molecule except for one modification. It does not contain a (exp(-hv, /2kT)(1-exp(-hv/kT)), vibrational contribution for motion along the one internal coordinate corresponding to the reaction path Second Order Saddle Point Transition structure a Transition Structure B Minimurn for Product A for Product B 05 Second Order o 0.5 Saddle paint Valley. Ridge for Reactant Infection Point Figure 8. 1 Typical Potential Energy Surface in Two Dimensions Showing Local Minima, Transition States and Paths Connecting them In the vicinity of the Ts, the reaction path can be identified as that direction along which the pes has negative curvature; along all other directions, the energy surface is positively curved. For example, in Fig 8. 1, a reaction path begins at Transition Structure B and is directed"downhill". More specifically, if one knows the gradients((aE/aSk))and3 There is, however, one aspect of the partition function of the TS species that is specific to this theory. The qAB* contains all of the usual translational, rotational, vibrational, and electronic partition functions that one would write down, as we did in Chapter 7, for a conventional AB molecule except for one modification. It does not contain a {exp(-hnj /2kT)/(1- exp(-hnj /kT))} vibrational contribution for motion along the one internal coordinate corresponding to the reaction path. Figure 8.1 Typical Potential Energy Surface in Two Dimensions Showing Local Minima, Transition States and Paths Connecting Them. In the vicinity of the TS, the reaction path can be identified as that direction along which the PES has negative curvature; along all other directions, the energy surface is positively curved. For example, in Fig. 8.1, a reaction path begins at Transition Structure B and is directed "downhill". More specifically, if one knows the gradients {(¶E/¶sk) }and