OPTICAL AND ELECTRON ENERGY LOSS SPECTRA OF LIQUID WATER: AN AB-INITIO STUDY

Water is the only common substance found naturally in all three common states of matter: solid, liquid, vapor. It is transparent, tasteless, odorless and ubiquitous. It is at the basis of life. Nevertheless, many issues concerning water are still a matter of debate. In this paper, we present ab-initio calculations of the excited state properties of liquid water in the framework of density functional theory and within the many-body Green's function formalism. In particular, the optical absorption spectrum with the inclusion of excitonic effects is calculated by solving the Bethe-Salpeter equation. The applicability and the accuracy of first-principles methods are also discussed.