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.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Density-functional
tight-binding (DFTB) parameters are presented
for the simulation of the bulk phases of zirconium. Electronic parameters
were obtained using a band structure fitting strategy, while two-center
repulsive potentials were created by particle swarm optimization.
As objective functions for the repulsive potential fitting, we employed
the Birch–Murnaghan equations of state for hexagonal close-packed
(HCP), body-centered cubic (BCC) and ω phases of Zr from density-functional
theory (DFT). When fractional atomic coordinates are not allowed to
change in the generation of the equation-of-state curves, long-range
repulsive DFTB potentials are able to almost perfectly reproduce equilibrium
structures, relative DFT energies of the bulk phases, and bulk moduli.
However, the same potentials lead to artifacts in the DFTB potential
energy surfaces when atom positions in the unit cell are allowed to
fully relax during the change of unit cell parameters. Conventional
short-range repulsive DFTB potentials, while inferior in their ability
to reproduce DFT bulk energetics, are able to correctly reproduce
the qualitative shape of the DFT potential energy surfaces, including
the location of global minima, and can therefore be considered more
transferable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.