Non-bonding Unpaired Electrons in Decorated Graphene
D. J. Klein
Foundational Sciences & MARS, Texas A&M University @ Galveston
Abstract
Graphene-based conjugated-carbon nano-structures are of significant interest for nanotechnologic applications. The most nearly non-bonding electrons are especially relevant, the moreso since the HOMO-LUMO gap collapses toward 0 as structures approach the graphene limit. But
there are very few nonbonding MOs in infinite graphene (at the tip of Dirac cones), so it is of
special relevance that a variety of defects or decorations of graphene (or of carbon nano-tubes)
yield additional non-bonding electrons, whose occurrence seems to depends simply on numbers
of “starred” & “unstarred” sites of degrees 1 & 2. For graphene boundaries there often turns out
to be boundary-localized electrons, as seen from a MO perspective, or especially easily from a
resonating VB perspective. With translational symmetry along the length of such a boundary (as
in a regular strip) a flat band of non-bonding orbitals can arise, yet be robust against localization
along the length of the boundary. This delocalization in the longitudinal direction while being
variably localized in the transvers direction gives rise to novel properties, as is to be discussed.
