  The electronic and magnetic properties of varying width,
oxygen-functionalized armchair graphene nanoribbons (AGNRs) are investigated
using first-principles density functional theory (DFT). Our study shows that
O-passivation results in a rich geometrical environment which in turn
determines the electronic and magnetic properties of the AGNR. For planar
systems a degenerate magnetic ground state, arising from emptying of O
lone-pair electrons, is reported. DFT predicts ribbons with ferromagnetic
coupling to be metallic whereas antiferromagnetically coupled ribbons present
three band gap families: one metallic and two semiconducting. Unlike hydrogen
functionalized AGNRs, the oxygen functionalized ribbons can attain a lower
energy configuration by adopting a non-planar geometry. The non-planar
structures are non-magnetic and show three semiconducting families of band gap
behavior. Quasiparticle corrections to the DFT results predict a widening of
the band gaps for all planar and non-planar, semiconducting systems. This
suggests that oxygen functionalization could be used to manipulate the
electronic structures of AGNRs.
