Ab-initio optical spectra of complex systems

We review the theoretical framework of ab-initio excited state properties calculations showing the application of these methods to systems of different dimensionality Many body perturbation theory within the GW approximation of the self energy for the calculation of electronic band structures is presented and applied to liquid water. The Bethe Salpeter equation for the computation of optical properties is illustrated and used for the case of surfaces and liquid water. An alternative method for the calculation of optical properties, the Time Dependent Density Functional Theory, is also briefly illustrated. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.