Structural and electronic properties of few‐layer graphenes from first‐principles

The first‐principles calculation method has been used to obtain structural and electronic properties of few‐layer graphenes (FLG's) with and without a cross‐film external electric potential, V ext . It is found that the AB stacking is more favorable than the AA stacking and the calculated layer spacing for the two‐layer AB stacked FLG is only 2.725 Å, which is substantially reduced from that of the bulk graphite of 3.257 Å. The two‐layer AB stacked FLG is found to exhibit a semi‐metal–semiconductor transition under V ext qualitatively in agreement with previous studies. However, the energy gap, E g , is not limited at 0.3 eV as obtained in previous first‐principles calculation due to the reduced interlayer spacing. The threshold of the semi‐metal–semiconductor transition is 0.04 Volts. V ext also induces E g 's in 3‐ and 4‐layer AB stacked FLG's. However, in these FLG's the induced E g 's are small within 0.1 eV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)