Recent progress in the fabrication and synthesis of quantum dots,
together with the rapid development of new measurement techniques at the
nanoscale, has lead to a wealth of experimental information on the electronic
and optical properties of semiconductor nanostructures. Yet, almost all
theoretical modeling for semiconductor quantum dots is based on continuum-like
models that cannot keep up with the atomistic-level physics revealed by
the new generation of experimental techniques.
I will present a new approach to nanoscale electronic structure calculations, based on an atomistic, plane-wave pseudopotential method, that provides the necessary accuracy and reliability to address experimental observations for semiconductor nanostructures ranging in size from 102 to 106 atoms. I will show how this method can be used to understand recently discovered nanoscale phenomena, such as the red-shift of the emission line in Si quantum dots, Coulomb blockade effects in InAs nanocrystals, multi-exciton recombination in self-assembled InAs/GaAs quantum dots, and Auger carrier relaxation in CdSe nanocrystals.
I will also discuss how this approach, coupled with an efficient algorithm
to search the space of atomic configurations, has lead to the solution
of the "inverse problem" of finding the atomic configuration of a semiconductor
alloy or superlattice having prescribed electronic and optical properties.