  A systematic study is made on geometric, electronic and magnetic properties
of one-dimensional graphene nanoribbons using the first-principles
calculations. The feature-rich essential properties result from the various
orbital hybridizations in chemical bonds and the edge-carbon- and
adatom-induced spin states. Pristine nanoribbons, with honeycomb lattices, can
exhibit the planar, curving, scrolling, folding, and stacking configurations.
Adatom adsorptions on surface and edge, respectively, create the buckled
structures and the non-hexagonal/non-planar edges. There exist six kinds of of
spin-dependent electronic and magnetic properties, non-magnetic, ferromagnetic
and anti-ferromagnetic metals, the non-magnetic semiconductors, and the
anti-ferromagnetic semiconductors with/without the spin splitting. They are
clearly illustrated by the energy gaps, the electron/hole densities, the net
magnetic moment, the atom-dominated energy bands, the spatial charge
distributions, the spin arrangements, and the orbital- and spin-projected
density of states. The diverse essential properties are determined by the
complicated relations among the finite-size confinement, edge structure,
curvature effect, interlayer atomic interaction, spin configuration, and
chemical adsorption. The theoretical predictions can provide the full
information in potential applications, and part of them agree with the recent
experimental measurements.
