We study the modifications on the ground and excited state properties of polycyclic aromatic hydrocarbons (PAHs), induced by the variation of concavity and π-connectivity. Inspired by experimentally feasible systems, we study three series of PAHs, from H-saturated graphene flakes to geodesic buckybowls, related to the formation of fullerene C60 and C50-carbon nanotube caps. Working within the framework of quantum chemistry semi-empirical methods AM1 and ZINDO/S, we find that the interplay between concavity and \pi-connectivity shifts the bright optical lines to higher energies, and introduces symmetry-forbidden dark excitations at low energy. A generally good agreement with the available experimental data supports our results, which can be viewed as the basis for designing optical properties of novel curved aromatic molecules.
@article{arxiv.1306.2766,
title = {Concavity Effects on the Optical Properties of Aromatic Hydrocarbons},
author = {Caterina Cocchi and Deborah Prezzi and Alice Ruini and Marilia J. Caldas and Annalisa Fasolino and Elisa Molinari},
journal= {arXiv preprint arXiv:1306.2766},
year = {2015}
}