Density functional theory calculations have been carried out to analyze the effect of
hydrogen halides and H2O molecule interactions with the three lowest energy isomers the
ring, bowl and cage of C20 fullerene. The single-point energy calculations have also been
performed at MP2/6-31+ G*//B3LYP/6-31G* level of theory. The complexes (C20⋯ H–X and
H2O, where X= F, Cl, and Br) are bounded by two interactions namely:(i) very weak X–H⋯ π
H-bond interactions and (ii) long range van der Waals interactions of H–X⋯ C type. These …