  The effect of external static charging of graphene and its flakes are
investigated by using first-principles calculations. While the Fermi level of
negatively charged graphene rises and then is quickly pinned by the parabolic,
nearly free electron like bands, it moves down readily by removal of electrons
from graphene. Excess charges accumulate mainly at both surfaces of graphite
slab. Even more remarkable is that Coulomb repulsion exfoliates the graphene
layers from both surfaces of positively charged graphite slab. The energy level
structure, binding energy and and spin-polarization of specific adatoms
adsorbed to a graphene flake can be monitored by charging.
