Electric fields in electronic structure calculations: Electric polarizabilities and IR and Raman spectra from first principles

By including an external electric field in first-principles electronic stru cture calculations we are able to explore a variety of properties of atomic clusters. In this paper we briefly discuss the technique and present sever al recent examples of its use, including the polarizabilities of Si cluster s, the IR spectra of hydrogenated Fe particles, and the Raman spectra of ch alcogenide glasses. The common feature in all these applications is that th ey involve predictions of directly observable properties. The value of the electric field calculations is thus that they produce a closer link between theory and experimental measurements.