  The production of multiple types of graphene, such as free standing,
epitaxial graphene on silicon carbide and metals, graphene in solution,
chemically grown graphene-like molecules, various graphene nanoribbons, and
graphene oxide with different levels of reduction and various chemical
composition, demonstrate the need for additional investigation beyond the basic
principles of graphene functionalization for avoidance of occasionally
contradictions between the predictions from first-principles simulations and
experimental results. Herein, we discuss the current state of modeling of the
different types of graphene using density functional theory (DFT) methods. We
focus on the static (substrate, shape, curvature, strain and doping) and
dynamic (starting point of functionalization, migration barriers and stability
of configurations) aspects that provide a more correct and selective modeling
of the chemisorption of various chemical species on the graphene scaffold.
Based on the recent modeling of experimentally realized functionalization of
different types of graphene we can conclude that the formation of uniform one-
or two-sided functionalized graphene discussed in earlier studies is an
exception to the typical scenarios of graphene chemistry. The presence of
different substrates, defects and lattice distortions, such as ripples and
strain, results in the formation of clusters or lines from the functional
groups. Several configurations of the chemical species on the graphene
substrate have been found to exist with ideal models but are only stable for
graphene functionalized under special conditions. The role of the technical
parameters, such as the functionals and computational methods employed, and the
important guidelines for the modeling of the chemical properties of various
types of graphene are also discussed.
