Methodological Investigation for Hydrogen Addition to Small Cage Carbon Fullerenes

Hydrogenated small fullerenes (Cn, n < 60) are of interest as potential astrochemical species, and intermediates in hydrogen-catalysed fullerene growth. However, the computational identification key stable species is difficult due to vast configurationally space structures. In this study, we explored routes predict hydrogenated fullerenes. We showed that neither local geometry nor electronic structure analysis was able correctly subsequent low-energy hydrogenation sites, sequential addition searches also sometimes failed identify most isomers. Of empirical semi-empirical methods tested, GFN2-xTB consistently gave highly accurate energy correlations (r > 0.99) full DFT-LDA calculations at a fraction cost. This allowed up 4H for four fullerenes, namely two isomers C28 C40, via “brute force” systematic testing all symmetry-inequivalent combinations. The approach shows promise wider studies smaller