  We discuss semiempirical approaches and parametric methods developed for
modeling molecular vibronic spectra. These methods, together with databases of
molecular fragments, have proved efficient and flexible for solving various
problems ranging from detailed interpretation of conventional vibronic spectra
and calculation of radiative transition probabilities to direct simulations of
dynamical (time-resolved) spectra and spectrochemical analysis of individual
substances and mixtures. A number of specific examples and applications
presented here show the potential of the semiempirical approach for predictive
calculations of spectra and solution of inverse spectral problems. It is
noteworthy that these advances provide computational insights into developing
theories of photoinduced isomer transformations and nonradiative transitions in
polyatomic molecules and molecular ensembles, theory of new methods for
standardless quantitative spectral analysis.

Chemical Physics;Computational Physics;Optics