Comment on “18 and 12 – Member carbon rings (cyclo[n]carbons) – A density functional study”

Recently, Iyakutti and coworkers published an interesting paper studying characteristics of cyclo[12]carbon and cyclo[18]carbon as well as their interactions with graphene (Mater. Sci. and Eng. B 263 (2021) 114895). However, we found some of their calculations are obviously unreasonable and a few conclusions are misleading. Here, we make some remarks on this paper according to common theoretical chemistry knowledge and our recent research experiences on cyclo[n]carbon systems, and meantime we revisit the interaction between the cyclo[18]carbon and graphene using a more reliable calculation model in combination with some novel analysis methods to provide complementary viewpoint to Iyakutti's work.