Optical properties of nanoalloys

The optical properties of multi-component metal nanostructures (or nanoalloys) are the subject of an intense and rapidly growing experimental and theoretical activity. In this perspective article, we first provide a survey of the most recent developments in the field, concerning both theoretical methods, especially at the first-principles level, and novel results, distinguishing for the convenience of presentation the sub-field of monolayer-protected multi-component metal clusters from the other alloy nanosystems. We then discuss a few general concepts which can be drawn from this survey, and offer a few suggestions on the most promising directions for future research. We hope that making the point in this fast developing field will provide a framework and a perspective useful to trigger future studies and advancements.