Miscellaneous Properties - UV Spectra, Ionization Energies, and Electron Affinities

5 Miscellaneous Properties - UV Spectra, Ionization Energies, and Electron Affinities 

All the properties that can be calculated by ab initio methods can in principle also be calculated semiempirically, bearing in mind that the more the molecule of interest differs from the training set used to parameterize the semiempirical program, the less reliable the results will be. For example, a program parameterized to predict the UV spectra of aromatic hydrocarbons may not give good predictions for the UV spectra of heterocyclic compounds. NMR spectra are usually calculated with ab initio (Section 5.5.5) or density functional (Chapter 7) methods. UV 

The concepts of IE and EA were discussed in Section 5.5.5. In Table 6.6 the results of some semiempirical calculations are compared with ab initio and experimental 

Wavelength (nm) Relative intensity Wavelength (nm) Relative intensity  

Dewar and Rzepa found that the MNDO (Section 6.2.5.3) electron affinities of 26 molecules with delocalized HOMOs (mostly radicals and conjugated organic molecules) had an absolute mean error of 0.43 eV for ten molecules with the 

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