  We investigate the currently debated issue of the existence of the Dirac cone
in silicene on an Ag(111) surface, using first-principles calculations based on
density functional theory to obtain the band structure. By unfolding the band
structure in the Brillouin zone of a supercell to that of a primitive cell,
followed by projecting onto Ag and silicene subsystems, we demonstrate that the
Dirac cone in silicene on Ag(111) is destroyed. Our results clearly indicate
that the linear dispersions observed in both angular-resolved photoemission
spectroscopy (ARPES) [P. Vogt et al, Phys. Rev. Lett. 108, 155501 (2012)] and
scanning tunneling spectroscopy (STS) [L. Chen et al, Phys. Rev. Lett. 109,
056804 (2012)] come from the Ag substrate and not from silicene.
