Investigasi struktur elektronik, magnetik dan optimasi termoelektrik heavily-doped Ca0.5La0.25Bi0.25MnO3 menggunakan metode komputasi DFT dan model restructured single parabolic band = Investigation of electronic and magnetic structures, and thermoelectric optimization of heavily-doped Ca0.5La0.25Bi0.25MnO3 using DFT computation method and restructured single parabolic band model