Nonlinear and Many-Body Effects on the Properties of Nanostructures

Jack Deslippe, University of California, Berkeley

The excitation spectra of nanostructures like 1D semiconducting single-walled carbon nanotubes (SWNTs) and 2D graphene sheets of 0D molecules is distinct from bulk semiconductors because of the large exciton binding energies of the excited states and the fact that every electronic state lies along a high symmetry direction. The excitation spectra is dominated by tightly correlated electron-hole states (excitons) of well-defined symmetry, as well as the corresponding exciton-phonon states. Probing the spectral structure of the different symmetries of SWNTs and other nanomaterials requires the use of nonlinear optics techniques such as ultrafast spectroscopy, two-photon spectroscopy and phonon-assisted spectroscopy. We present an extension of the first-principles GW-Bethe Salpeter approach to calculating these properties and present calculations on the nonlinear optical properties of nanostructures.

Abstract Author(s): Jack Deslippe, David Prendergast and Steven G. Louie