Binding energy and nature of the orbitals in fluorinated graphene: a density functional theory study

TL;DR

This study uses density functional theory to analyze fluorine adsorption on graphene, revealing stable fluorine dimers, clustering tendencies, and detailed orbital hybridizations, advancing understanding of fluorinated graphene's electronic structure.

Contribution

The paper provides new insights into fluorine adatom stability, clustering behavior, and orbital hybridization in fluorinated graphene through detailed DFT calculations.

Findings

Fluorine dimers are stable against dissociation.

Fluorination occurs via neighboring carbon atoms on different sublattices.

Orbital rehybridization is quantified as sp extsuperscript{2.33} and sp extsuperscript{4.66}.

Abstract

We present density functional theory calculations of the binding energies of one, two and three fluorine adatoms on the same side of monolayer graphene. We show that fluorine dimers on graphene in a spin-singlet state are stable against dissociation into isolated fluorine adatoms, suggesting that there is a tendency for fluorine adatoms on a single side of graphene to cluster. Our results suggest that fluorination develops by successive bonding of fluorine atoms to neighbouring carbon atoms on different sublattices, while the spins are arranged to reduce the total magnetisation of the ground state. We find that the finite-size error in the binding energy of a single fluorine atom or dimer on a periodic supercell of graphene scales inversely with the cube of the linear size of the simulation supercell. By using $\pi$-orbital axis analysis, the rehybridisation of the three $\sigma$-orbitals pointing directly along the bonds to the central fluorinated carbon is found to be sp\textsuperscript{2.33}. The rehybridisation of the carbon orbital in the C--F bond is found to be sp\textsuperscript{4.66}.