Computation of spectroscopic parameters in vacuo and in condensed phases by methods based on the density functional theory.

The impact of density functional theory in the computation of reliable spectroscopic parameters is reviewed with special reference to IR, Raman, UV, visible, NMR and EPR techniques. In general terms, the results delivered by the most recent density functionals (especially hybrid ones) are remarkably accurate. Proper treatment of solvent effects by continuum models and of vibrational averaging effects by suitable Hamiltonians governing the nuclear motions. significantly increases the reliability of the results and the fields of application of theoretical computations. Some case examples have been reported to better illustrate the potentialities of this approach also for non specialists.