The focus of this thesis is computationally designing inorganic scintillators previously predicted by informatics, which have not been validated computationally. Density Functional Theory (DFT) calculations were performed to (1) select garnet host lattices that are good scintillators, thereby down selecting from compounds previously identified via informatics, and (2) identify co-dopant chemistries in perovskites which enhance scintillator property. In this thesis, the property of focus is bandgap, which in general has an inverse correlation to light yield. The total energy code Cambridge Sequential Total Energy Package (CASTEP) was used for performing DFT calculations, taking advantage of its speed in modeling the electronic structure of the complex inorganic scintillators. From our calculations, Tb3Al2Ga3O12 was identified as forming a stable garnet structure and having a modeled direct bandgap corresponding with light yield better than other similar garnet host lattices. Further, from our calculations, we find four co-dopant chemistries which improve the bandgap from singly doped perovskites.