Artificial molecules

Double semiconductor nanocrystals, called artificial molecules by analogy to artificial atoms (quantum dots), are investigated. Empirical tight-binding and k.p theories are used to obtain electronic structure, charge density distributions, and optical absorption spectra for single and double nanocrystals. We show how the bonding and antibonding molecular orbitals are formed from the wavefunctions of individual nanocrystals when the nanocrystals are joined together to form an artificial molecule. Formation of quantum dot lattices and interpretation of experimental data for close-packed solids of nanocrystals are discussed. (C) 2002 Wiley Periodicals, Inc.