where vF = 3aτ /(2ℏ) ≈ 9 • 10 5 m/s is the velocity corresponding to the Fermi energy within graphene, a ≈ 1.42 Å corresponds to the nearest-neighbor distance and τ ≈ 2.7 eV is the hopping energy between neighbors. The latter part describes any dopingrelated processes and is equal to