  We have investigated the way in which the concentration and distribution of
adatoms affect the geometric and electronic properties of graphene. Our
calculations were based on the use of first principle under the density
functional theory which reveal various types of $\pi$-bonding. The energy band
structure of this doped graphene material may be explored experimentally by
employing angle-resolved photo-emission spectroscopy (ARPES) for electronic
band structure measurements and scanning tunneling spectroscopy (STS) for the
density-of-states (DOS) both of which have been calculated and reported in this
paper. Our calculations show that such adatom doping is responsible for the
destruction or appearance of the Dirac cone structure.
