  The electronic properties of monolayer tin dulsulphide (ML-SnS2), a recently
synthesized metal dichalcogenide, are studied by a combination of
first-principles calculations and tight-binding (TB) approximation. An
effective lattice Hamiltonian based on six hybrid sp-like orbitals with
trigonal rotation symmetry are proposed to calculate the band structure and
density of states for ML-SnS2, which demonstrates good quantitative agreement
with relativistic density functional theory calculations in a wide energy
range. We show that the proposed TB model can be easily applied to the case of
an external electric field, yielding results consistent with those obtained
from full Hamiltonian results. In the presence of a perpendicular magnetic
field, highly degenerate equidistant Landau levels are obtained, showing
typical two-dimensional electron gas behavior. Thus, the proposed TB model
provides a simple new way in describing novel properties in ML-SnS2.
