Unique Bonding Nature of Carbon-Substituted Be₂ Dimer inside the Carbon (sp²) Network

Abstract

Controlled doping of active carbon materials (viz., graphenes, carbon nanotubes etc.) may lead to the enhancement of their desired properties. The least studied case of C/Be substitution offers an attractive possibility in this respect. The interactions of Be₂ with Be or C atoms are dominated by the large repulsive Pauli exchange contributions, which in turn offsets the attractive interactions leading to relatively small binding energies. The Be₂ dimer, e.g., after being doped inside a planar carbon network, undergoes orbital adjustments due to charge transfer and unusual intermolecular interactions and is oriented perpendicular to the plane of the carbon network with the Be–Be bond center located inside the plane. The present theoretical investigation on the nature of bonding in C/Be₂ exchange complexes, using state of the art quantum chemical techniques, reveals a sp² carbon-like bonding scheme in Be₂ arising due to the molecular hybridization of σ and two π orbitals. The perturbations imposed by doped Be₂ dimers exhibit a local character of the structural and electronic properties of the complexes, and the separation by two carbon atoms between beryllium active centers is sufficient to consider these centers as independent sites