Edge Functionalization and Optical Excitations in Graphene Nanoflakes

We investigate the effects of edge covalent functionalization on the opto-electronic properties of finite elongated graphene nano-flakes (GNFs). Following our previous work on nanojunctions[1], we compute mean-field ground state electronic properties and configuration-interaction UV-vis optical excitations at varying size and functionalization by means of semi-empirical methods. The character of the lowest energy excitations and the influence exerted on them both by length/width modulation and by the specific chemical properties of the terminating groups are analyzed in details. The role of local distortions spontaneously arising upon geometrical optimization is inspected. Nanoplasmonic-like features related to the spectrum of these elongated finite graphene nanostructures are also discussed. [1] C. Cocchi et al. J. Phys. Chem. Lett. 2, 1315 (2011)