The Vienna ab-initio simulation package (VASP) and Density Functional Theory (DFT) calculation method are used to study the structural and detailed electronic properties through atomic substitution in the CH₃NH₃Pb_(1-x)Y_(x)I₃ (YSr, Ca x = 0.125, 0.25, 0.50, 0.75, and 1.0) perovskites. We determined that the non-stoichiometric crystal structures were calculated as a distorted orthorhombic phase as predicted by the tolerance factor range 0.7 < t < 0.9. The bandgaps of the stoichiometric CH₃NH₃SrI₃ and CH₃NH₃CaI₃ compounds are calculated 3.261 eV (Q → Γ indirect) and 3.144 eV (Q → Γ indirect), respectively and they are very high for ideal photo absorbers. We were determined that the bandgap (Γ → Γ direct) of the CH₃NH₃Pb_0.875Ca_0.125I₃, CH₃NH₃Pb_0.750Ca_0.250I₃, and CH₃NH₃Pb_0.875Sr_0.125I₃ compounds are calculated 1.44 eV, 1.54 eV, and 1.525 eV respectively and are more suitable for ideal photo absorbers. It was seen that Ca²⁺ substitution was more successful than Sr²⁺ substitution.

维也纳Ab-initio模拟程序包（VASP）和密度泛函理论（DFT）计算方法用于通过在CH ₃ NH ₃ Pb _（1-x） Y _（x） I _3中进行原子取代来研究结构和详细的电子性质（Y Sr，Ca x = 0.125、0.25、0.50、0.75和1.0）钙钛矿。我们确定非化学计量的晶体结构被计算为畸变的正交晶相，如公差因子范围0.7 <t <0.9所预测的。化学计量CH的带隙₃ NH ₃ SRI ₃和CH ₃ NH ₃了Cal ₃分别计算出3.261 eV（Q→Γ间接）和3.144 eV（Q→Γ间接）的化合物，对于理想的光吸收剂来说它们非常高。我们确定计算出CH ₃ NH ₃ Pb _0.875 Ca _0.125 I ₃，CH ₃ NH ₃ Pb _0.750 Ca _0.250 I ₃和CH ₃ NH ₃ Pb _0.875 Sr _0.125 I ₃化合物的带隙（Γ→ΓDirect）分别为1.44 eV，1.54 eV和1.525 eV，更适合理想的光吸收剂。可以看出，Ca ²⁺取代比Sr ²⁺取代更成功。