The nature of bonding and electronic properties of graphene and benzene with iridium adatoms

Autor(en)

Petr Lazar, Jaroslav Granatier, Jiri Klimes, Pavel Hobza, Michal Otyepka

Abstrakt

Recent theoretical simulations predicted that graphene decorated with Ir

adatoms could realize a two-dimensional topological insulator with a

substantial band gap. Our understanding of how the electronic properties

of graphene change in the presence of metal adatoms is however still

limited, as the binding is quite complex involving static and dynamic

correlation effects together with relativistic contributions, which

makes the theoretical description of such systems quite challenging. We

applied the quantum chemical complete active space second order

perturbation theory (CASPT2) method and density functional theory beyond

the standard local density functional approach including relativistic

spin–orbit coupling (SOC) effects on Ir–benzene and Ir–graphene

complexes. The CASPT2-SOC method revealed a strong binding affinity of

Ir for benzene (33.1 kcal mol⁻¹) at a 1.81 Å distance, which was of a single reference character, and a weaker binding affinity (6.3 kcal mol⁻¹)

at 3.00 Å of a multireference character. In the Ir–graphene complex,

the quartet ground-state of the Ir atom changed to the doublet state

upon adsorption, and the binding energy predicted by optB86b-vdW-SOC

functional remained high (33.8 kcal mol⁻¹). In

all cases the dynamic correlation effects significantly contributed to

the binding. The density of states calculated with the hybrid functional

HSE06 showed that the gap of 0.3 eV was induced in graphene by the

adsorbed Ir atom even in scalar relativistic calculation, in contrast to

metallic behaviour predicted by local density approximation. The

results suggest that the strong correlation effects contribute to the

opening of the band gap in graphene covered with the Ir adatoms. The

value of the magnetic anisotropy energy of 0.1 kcal mol⁻¹ predicted by HSE06 is lower than those calculated using local functionals.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Czech Academy of Sciences, Slovak University of Technology in Bratislava, Olmützer Palacky-Universität

Journal

Physical Chemistry Chemical Physics

Band

16

Seiten

20818-20827

Anzahl der Seiten

10

ISSN

1463-9076

DOI

https://doi.org/10.1039/c4cp02608j

Publikationsdatum

2014

Peer-reviewed

Ja

ÖFOS 2012

103025 Quantenmechanik, 103036 Theoretische Physik, 103015 Kondensierte Materie, 103009 Festkörperphysik

Schlagwörter

ASJC Scopus Sachgebiete

Allgemeine Physik und Astronomie, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/9936f908-1d41-43b1-b8aa-51b4404fabf0