This study explores the structural, cohesive energy, optical, electronic and the photoluminescence property of silicon oxide structure and doped with carbon (C) and mercury (Hg) using Density Functional Theory (DFT). Result for the structural property calculation indicate an increase in the optimized lattice parameter and density of the structures due to the doping of Hg and C. The result for the cohesive energy calculation is -7.7036 for the pristine structure, -0.5231 and -0.3999 due to the doping of C and Hg which decreases the system dynamical stability. The electronic properties calculation of the structures were studied using the Generalized Gradient Approximation (GGA), the result obtained is an indirect wide band gap insulator with 9.8 eV for the pristine SiO2 and 6.6 eV, 5.6 eV respectively for doped C and Hg. The result is in agreement with previous DFT studies and slightly above the reported experimental data. The substitutional doping of Hg and C significantly reduces the energy band gap which is the contributory factor for the enhance photoluminescence of the structure. Optical properties were also obtained from the dielectric function of real and imaginary part, the absorption coefficient, extinction coefficient, reflectivity and refractive index were also calculated.