The band gaps and optoelectronic properties of binary calcium chalcogenide semiconductors have been modified theoretically by doping magnesium atom(s) into their respective rock-salt unit cells at some specific concentrations $x$ = 0.0, 0.25, 0.50, 0.75 and 1.0 and confirmed such modifications by studying their structural, electronic and optical properties using DFT based FP-LAPW approach. The WC-GGA functional is used to calculate structural properties, while mBJ, B3LYP and WC-GGA are used for calculating electronic and optical properties. The concentration dependences of lattice parameter, bulk modulus and fundamental band gap for each alloy system exhibit nonlinearity. The atomic and orbital origin of different electronic states in the band structure of each compound are explored from its density of states (DOS). The microscopic origin of band gap bowing for each of the alloy systems is explored in terms of volume deformation, charge exchange and structural relaxation. The chemical bonds between the constituent atoms in each compound are found as ionic in nature. Optical properties of each specimen are calculated from its computed spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.

从理论上讲，通过将镁原子以一定的特定浓度掺杂到其各自的盐岩晶胞中，可以改善二元硫属元素钙化物半导体的带隙和光电性能。 $X$= 0.0、0.25、0.50、0.75和1.0，并通过使用基于DFT的FP-LAPW方法研究其结构，电子和光学性质，确认了此类修饰。WC-GGA功能用于计算结构特性，而mBJ，B3LYP和WC-GGA用于计算电子和光学特性。每个合金体系的晶格参数，体积模量和基带隙的浓度依赖性表现出非线性。从每个化合物的能带密度（DOS）探索了每种化合物的能带结构中不同电子态的原子和轨道起源。从体积变形，电荷交换和结构弛豫方面探讨了每种合金体系的带隙弯曲的微观起源。自然界中发现每种化合物中构成原子之间的化学键都是离子性的。每个样品的光学特性均由其计算出的介电函数，折射率，消光系数，法向入射反射率，光导率，光吸收和能量损失函数的光谱计算得出。已将一些计算结果与可用的实验数据和其他理论数据进行了比较。