Interaction Energy of a Water Molecule with a Single-Layer Graphitic Surface Modeled by Hydrogen- and Fluorine-Terminated Clusters

Abstract

In ab initio calculations a finite graphitic cluster model is often used to approximate the interaction energy of a water molecule with an infinite single-layer graphitic surface (graphene). In previous studies, the graphitic cluster model is a collection of fused benzene rings terminated by hydrogen atoms. In this study, the effect of using fluorine instead of hydrogen atoms for terminating the cluster model is examined to clarify the role of the boundary. The interaction energy of a water molecule with the graphitic cluster was computed using ab initio methods at the MP2 level of theory and with the 6-31G(d = 0.25) basis set. The interaction energy of a water molecule with graphene is estimated by extrapolation of two series of increasing size graphitic cluster models (C(6n2)H(6n) and C(6n2)F(6n), n = 1-3). Two fixed orientations of water molecule are considered: (a) both hydrogen atoms of water pointing toward the cluster (mode A) and (b) both hydrogen atoms of water pointing away from the cluster (mode B). The interaction energies for water mode A are found to be -2.39 and -2.49 kcal/mol for C(6n2)H(6n) and C(6n2)F(6n) cluster models, respectively. For water mode B, the interaction energies are -2.32 and -2.44 kcal/mol for C(6n2)H(6n) and C(6n2)F(6n) cluster models, respectively.

Molecular origin of drug release by water boiling inside carbon nanotubes from reactive molecular dynamics simulation and DFT perspectives

“…We used the TZVP(-f) basis set for the total energy ( E tot ) calculation. Our DFT-revPBE-D3 results showed an interaction energy of −0.127 eV (−2.929 kcal/mol) with average equilibrium distance (distance between H atom from H 2 O and C atom of graphene) of about 2.605 Å which are in good agreement with high-level quantum chemistry based calculations at the MP2 as well as CCSD(T) level of theory 95, 96 . The reported interaction energy and equilibrium distance between interacting molecules at the CCSD(T) level were determined to be −0.135 eV and 2.69 Å 95 , respectively, while MP2 method 96 estimated −0.103 eV and 2.70 Å for the interaction energy and equilibrium distance, respectively.

Figure 5Optimized structures with DFT - revPBE-D3/SVP method for ( a ) H 2 O and ( b ) benzene molecules adsorbed onto graphene flake (All distances are in Å).

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Water on BN doped benzene: A hard test for exchange-correlation functionals and the impact of exact exchange on weak binding

“…[17][18][19] Despite the growing number of studies for water on h-BN [20][21][22] and graphene 15,16,[23][24][25][26][27] there are no direct measurements of adsorption energies for the water monomer, and the theoretical adsorption energies for these systems vary significantly across different high accuracy methods. 25,[27][28][29] One can use smaller model systems for graphene 25,[29][30][31][32] and h-BN, such as benzene and the inorganic counterpart borazine (B 3 N 3 H 6 ), to help understand the interaction with water. With these small molecules, it is possible to use high accuracy methods to calculate benchmark interaction energies and binding conformations, [33][34][35][36][37] that would otherwise be infeasible for the extended surfaces.…”

Water Clusters on Graphitic Carbon Surfaces

“…By the MP2/ 6-31 ? G(0.25) level of theory, Sudiarta and Geldart found the water-graphene interaction to be about -10 kJ/mol, based on the extrapolation of the interaction energies of water-benzene, water coronene, and water-circumcoronene [26]. Similar interaction energy has been obtained from the extrapolation of the perfluorinated analogues.…”

“…It is expected that the formation of water clusters on the surface will probably result in excessively large interaction energy for an isolated water molecule. Molecular-level understanding of the interactions of water clusters with graphitic materials and their influence on macroscopic phenomena is certainly among the main topics of scientists [4][5][6][7][8][9][10][11][12][13][14][21][22][23][24][25][26]. However, at the quantum mechanical level, such understanding is still far from complete, with the most fundamental matter between water molecules and any carbon surface yet to be fully established.…”