Pérez-Guardiola, Andrés, Ortiz-Cano, Ricardo, Sandoval-Salinas, María Eugenia, Fernández-Rossier, Joaquín, Casanova, David, Pérez-Jiménez, Ángel J., Sancho-Garcia, Juan-Carlos From cyclic nanorings to single-walled carbon nanotubes: disclosing the evolution of their electronic structure with the help of theoretical methods Physical Chemistry Chemical Physics. 2019, 21: 2547-2557. doi:10.1039/C8CP06615A URI: http://hdl.handle.net/10045/88413 DOI: 10.1039/C8CP06615A ISSN: 1463-9076 (Print) Abstract: We systematically investigate the relationships between structural and electronic effects of finite size zigzag or armchair carbon nanotubes of various diameters and lengths, starting from a molecular template of varying shape and diameter, i.e. cyclic oligoacene or oligophenacene molecules, and disclosing how adding layers and/or end-caps (i.e. hemifullerenes) can modify their (poly)radicaloid nature. We mostly used tight-binding and finite-temperature density-based methods, the former providing a simple but intuitive picture about their electronic structure, and the latter dealing effectively with strong correlation effects by relying on a fractional occupation number weighted electron density (ρFOD), with additional RAS-SF calculations backing up the latter results. We also explore how minor structural modifications of nanotube end-caps might influence the results, showing that topology, together with the chemical nature of the systems, is pivotal for the understanding of the electronic properties of these and other related systems. Keywords:Organic nanorings, Cyclacenes, Cyclophenacenes, SWCNT, End-capping, Fractional orbital occupation, FT-DFT, RAS-SF Royal Society of Chemistry info:eu-repo/semantics/article