Physisorption Of Nucleobases On Graphene: A Comparative Van Der Waals Study

The physisorption of the nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) on graphene is studied using several variants of the density functional theory (DFT): the generalized gradient approximation with the inclusion of van der Waals interaction (vdW) based on the TS approach (Tkatchenko and Scheffer 2009 Phys.Rev.Lett.102 073005) and our simplified version of this approach (here called sTS), the van der Waals density functional vdW-DF (Dion etal 2004 Phys.Rev.Lett.92 246401) and vdW-DF2 (Lee etal 2010 Phys.Rev.B 82 081101), and DFT-D2 (Grimme 2006 J.Comput.Chem. 27 1787) and DFT-D3 (Grimme etal 2010 J.Chem.Phys.132 154104) methods. The binding energies of nucleobases on graphene are found to be in the following order: G\u3eA\u3eT\u3eC\u3eU within TS, sTS, vdW-DF, and DFT-D2, and in the following order: G\u3eA\u3eTC\u3eU within DFT-D3 and vdW-DF2. The binding separations are found to be different within different methods and in the following order: DFT-D2 \u3c TS \u3c DFT-D3vdW-DF