Browsing by Subject "Plane wave calculations"

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    Effects of silicon and germanium adsorbed on graphene
    (A I P Publishing LLC, 2010) Aktürk, E.; Ataca, C.; Çıracı, Salim
    Based on the first-principles plane wave calculations, we studied the adsorption of Si and Geon graphene. We found that these atoms are bound to graphene at the bridge site with a significant binding energy, while many other atoms are bound at the hollow site above the center of hexagon. It is remarkable that these adatoms may induce important changes in the electronic structure of graphene even at low coverage. Semimetallic graphene becomes metallized and attains a magnetic moment. The combination of adatom orbitals with those of ππ- and π∗π∗-states of bare graphene is found responsible for these effects.
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    High-capacity hydrogen storage by metallized graphene
    (AIP Publishing, 2008) Ataca, C.; Aktürk, E.; Çıracı, Salim; Ustunel H.
    First-principles plane wave calculations predict that Li can be adsorbed on graphene forming a uniform and stable coverage on both sides. A significant part of the electronic charge of the Li 2s orbital is donated to graphene and is accommodated by its distorted π* -bands. As a result, semimetallic graphene and semiconducting graphene ribbons change into good metals. It is even more remarkable that Li covered graphene can serve as a high-capacity hydrogen storage medium with each adsorbed Li absorbing up to four H2 molecules amounting to a gravimetric density of 12.8 wt %.