XYZ molecules

Most XYZ molecules, especially those with mx very different from mz (for example, HCN) have local behavior. The situation is very different in XY2 molecules, for which the two bonds are identical. Thus, one must have... 

The local-to-normal transition is governed by the same parameter of Eq. (4.30). The difference is that now the local-to-normal transition occurs simultaneously for the stretching and bending vibrations. The correlation diagram for stretching vibrations is the same as in Figure 4.3. The local-to-normal transition can also be studied for XYZ molecules, for which the Hamiltonian does not have the condition A) = A2 and is... 

For bent XYZ molecules there are several possible choices of geometrical variables, as discussed in Chapter 3. 

Table 6 Total atomic population Gt on atom i in some linear XYZ molecules with different basis sets424...

If the moments / of more than one species are required to determine the molecular structure, this averaging is no longer feasible. The -structure must then be obtained by direct calculation (or by a least-squares fit, if possible) using a substitution data set composed in a completely balanced manner of complementary sets of isotopomers. The linear XYZ molecule, e.g., is a problem which must be treated in this way. This restructure is still expected to approximate the restructure better than the restructure does. 

For the linear XYZ molecule, with two non-degenerate and one doubly degenerate vibrations, one Bg value and three a values must be determined ... 

Let us now investigate the effects which the two different models proposed for the activated state have upon the quantities kjk a, The difference in degeneracy between the two models will introduce a change of ten per cent at the most on account of the small magnitude of l+J(Wj,+ ) /24. In considering the contributions of the entropy terms to i/ 2a finds, from Lechner s formulas for the vibrations of a bent XYZ molecule, that the ratio (vi rather insensitive to... 

For the reaction of Problem 9.2 compute the /1-factor assuming the CIHH angle to be 90°. For an XYZ molecule with such geometry the moment of inertia product is... 

Here [7°]i (g = 1) is the ground-state moment of the parent isotopic species and [7 ]i is the substitution moment of inertia calculated from the set of substitution coordinates of the parent species. The dataset, the L isotopic species, is that needed for evaluation of a complete substitution structure. For a linear XYZ molecule, four isotopic species (including the parent) are needed for the substitution structure. From Eqs. (99) and (98), it follows for the parent, g = 1, that [7 ]i = 7 . The rationale for... 

---