Optical properties of doped nanocrystals from correlated quantum chemistry

Doped nanocrystals exhibit infrared absorption and are promising candidates for sensors, solar enegy conversion, and optical communications. The infrared absorption appears to undergo a transition from a single-particle to plasmonic absorption as a function of doping density and radius. This transition is not well understood from an experimental or theoretical point of view. This talk will present results from correlated quantum chemistry calculations of a particle-in-a-sphere model for a doped nanocrystal. The transition of the infrared absorption from single-particle to plasmonic is found to also depend on the absolute number of doped electrons. In particular, a single-particle transition can be broken into true single-particle, and Coulombically bound, but collective, excitations. These results highlight the importance of many-body exchange and correlation effects in quantum confined nanostructures.