  Ab initio density functional theory calculations are carried out to predict
the electronic properties and relative stability of gallium sulfide nanoribbons
(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. It is found that
the electronic properties of the nanoribbons are very sensitive to the edge
structure. The zigzag nanoribbons (Ga2S2-ZNRs) are metallic with spin-polarized
edge states regardless of the H-passivation,whereas the bare armchair ones
(Ga2S2-ANRs) are semiconducting with an indirect band gap. This band gap
exhibits an oscillation behavior as the width increases and finally converges
to a constant value. Similar behavior is also found in H-saturated Ga2S2-ANRs,
although the band gap converges to a larger value. The relative stabilities of
the bare ANRs and ZNRs are investigated by calculating their binding energies.
It is found that for a similar width the ANRs are more stable than the ZNRs,
and both are more stable than some Ga2S2 nanocluters with stable
configurations.
