  The structural, electronic, and dielectric (optical) properties of
graphene-like 2D MgO monolayer have been explored through first-principles
calculations under bi-axial tensile and compressive mechanical strain within a
range of -10% to +10%. Our findings revealed that the pristine MgO monolayer is
an indirect band gap semiconducting material and the semiconducting mature of
MgO monolayer remains consistent under both compressive and tensile mechanical
strain. This nature of MgO is confirmed through partial density of states
(PDOS) as well as electronic band structure. PDOS exhibits the contribution of
different atomic orbitals in bond formation and nature of bond, while band
structure provides insight into electron transitions between energy levels of
valance and conduction bands. All optical parameters (dielectric function,
reflectivity, energy loss, refractive index, extinction coefficient and
absorption) are plotted in an energy range 0-15 eV. Within this energy
interval, MgO possesses the highest value of the refractive index (2.13) at
3.12 eV energy. Also, a detailed analysis of changes in the geometrical
structure of MgO monolayer is provided.
