Double-Hybrid Functionals and Tailored Basis Set: Fullerene (C) Dimer and Isomers as Test Cases.

A computational protocol making use of double hybrid functionals in conjunction with a recently developed basis set tailored to reproduce noncovalent interactions (hereafter named DH-SVPD) is here applied and tested for the evaluation of the properties of C fullerenes, namely intermolecular interactions in the weakly bound C dimer and relative stabilities of C isomers (as described by the C60ISO and iso-C60 data sets). The obtained results suggest that the DH-SVPD performance is very close to that obtained with empirical corrections and larger quadruple-ζ basis for the C dimer. In contrast, both approaches (tailored basis set and larger basis with empirical potential) do not reach the envisaged accuracy for the relative stabilities of C isomers. Nevertheless, this test well underlined how the DH-SVPD basis set is able to recover the performance obtained by coupling the DH functionals with empirical dispersion corrections and larger basis set, significantly reducing the computational effort for double hybrids and thus enabling expansion of their application domain to larger molecular systems.