Abstract
We report a quantum mechanical description based on the density
functional theory of the structures and electronic properties of
armchair boron nitride nanoribbons (BNNRs) edge-terminated with O atoms
and OH groups. The O edge termination was found to give a peroxide-like structure that is nonmagnetic and semiconducting with a bandgap of E-g =
2.8 eV. The O-terminated BNNR ribbon was stabilized by the reduction of
the peroxide groups with H atoms leading to a polyol-like structure. The
two chains of hydrogen bonds created along the edges lead to alternating
5- and 7-membered rings and cause the ribbon to become nonplanar with
rippled edges. Three configurations of different ripple periods and
amplitudes were found with energy differences up to 2 eV per unit cell but with virtually the same bandgap of E-g = 4.2 eV. The hydrogen bond
mediated ripples are characterized through the lone pair orbitals
showing a local a sigma-pi separation and a pair of ``rabbit-ears'' on
the acceptor O atoms in 5- and 7-membered rings respectively dictated by
the hydrogen bond lengths. Energy bands and total and projected density
of states are discussed for both functionalizations to show their
effects on altering the electronic properties of armchair BNNRs.
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