Coupled Cluster and Density Functional Studies of Atomic Fluorine Chemisorption on Coronene as Model Systems for Graphene Fluorination

Abstract

Potential energy curves (PECs) of atomic fluorine adsorption on coronene as a model for graphene or nanocarbon surfaces have been computed. The PECs were obtained by scanning the fluorine atom distance to one of the center carbon atoms of the coronene molecule as model system in a “top” position from 4.0 to1.0 Å in intervals of 0.1 Å using a variety of quantum chemical methods. Various density functional theory (DFT) functionals, such as B3LYP, PBE, PBE0, CAM-B3LYP, and LC-ωPBE; approximate DFT methods such as several levels of the density-functional tight-binding (DFTB) method, as well as ab initio wave function theory methods such as MP2, CCSD, CCSD­(T), and G2MS extrapolations, were used to evaluate energies for B3LYP/cc-pVDZ PEC geometries. G2MS is an approximation to the highly accurate CCSD­(T)/cc-pVTZ level of theory in our work. We found that fluorine is chemically adsorbed on coronene with a binding energy of 22.9 and 23.3 kcal/mol at the B3LYP/cc-pVDZ and G2MS levels of theory, respectively, and 18.3 and 19.3 kcal/mol after counterpoise correction. Additionally, we found that pure DFT functionals and their DFTB approximations fail to predict the correct dissociation limit due to the DFT-inherent self-interaction error and various limitations in the DFTB approximation itself.

Theoretical Study of Oxygen Atom Adsorption on A Polycyclic Aromatic Hydrocarbon Using Density-Functional Theory

“…Thus, we might suspect that the previous reports were using PBE-PAW as their level of theory. PBE is also known to underestimate the interaction energy, as we encountered earlier [33][34].…”

“…In this theoretical study, we investigated atomic O attack and chemisorption on coronene (C24H12), a PAH, by using density functional theory (DFT). Coronene has also been consistently employed as a model of graphene for the atom-graphene interaction studies [30][31][32][33][34]. We showed plausible reaction intermediates, transition states, and products.…”

“…The potential energy calculations on the distance between the O atom and the coronene sheet at the "top" site or "bridge" site were carried out to observe the interaction of the O atom that may form a single bond or two single bonds with the C atom in the coronene sheet respectively, while the attack at "hollow" site was not considered because the O atom attack at the site will be energetically unfavorable since the interaction energy indicated repulsive as in the case of H and F [33][34]. As shown in Fig.…”

“…We applied unrestricted B3LYP [35] density functional with the cc-pVDZ basis set to scan the relaxed "top" and "bridge" sites and full optimizing calculations of the stationary points. The B3LYP/cc-pVDZ level of theory is accurate enough to give the adsorption energy because the energies in the analogous system of coronene with H and F atom evaluated at the same level of theory, B3LYP/cc-pVDZ were similar to the energies estimated by the correlated ab initio wave function method to the complete basis set limit [33][34]. All computations performed in this work were carried out using Gaussian 09 program package [36].…”

A Theoretical Study on Vibrational Energies of Molecular Hydrogen and Its Isotopes Using a Semi-classical Approximation

“…Moreover, DFT was used along with ab-initio correlated wavefunction theory (WFT) methods to obtain highly accurate potential energy curves (PECs) of fluorine adsorption on coronene [23], setting up a high-level benchmark for theoretical studies on graphene functionalization. The results generated from the abovementioned first-principle calculations are in excellent agreement with their corresponding experimental values and other ab-initio products.…”