arXiv subjects

Giovanni Bussi

Publications and source records attributed to Giovanni Bussi.

74 records · Page 5Linked to original sources

arXiv2004

Excitons in carbon nanotubes: an ab initio symmetry-based approach

The optical absorption spectrum of the carbon (4,2) nanotube is computed using an ab-initio many-body approach which takes into account excitonic effects. We develop a new method involving a local basis set which is symmetric with respect to the screw symmetry of the tube. Such a method has the advantages of scaling faster than plane-wave methods and allowing for a precise determination of the symmetry character of the single particle states, two-particle excitations, and selection rules. The binding energy of the lowest, optically active states is approximately 0.8 eV. The corresponding exciton wavefunctions are delocalized along the circumference of the tube and localized in the direction of the tube axis.

cond-mat.mtrl-sci↗

arXiv2002

Solid state effects on exciton states and optical properties of PPV

We perform ab initio calculations of optical properties for a typical semiconductor conjugated polymer, poly-para-phenylenevinylene, in both isolated chain and crystalline packing. In order to obtain results for excitonic energies and real-space wavefunctions we explicitly include electron-hole interaction within the density-matrix formalism. We find that the details of crystalline arrangement crucially affect the optical properties, leading to a richer exciton structure and opening non-radiative decay channels. This has implications for the optical activity and optoelectronic applications of polymer films.

cond-mat.mtrl-sci↗