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 structure calculations we are able to explore a variety of properties of atomic clusters. In this paper we briefly discuss the technique and present several recent examples of its use, including the polarizabilities of Si clusters, the IR spectra of hydrogenated Fe particles, and the Raman spectra of chalcogenide glasses. The common feature in all these applications is that they 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.