Periodic first-principles calculations based on density functional theory at the B3LYP level has been carried out to investigate the photoluminescence (PL) emission of BaZrO3 assembled nanoparticles at room temperature. The defect created in the nanocrystals and their resultant electronic features lead to a diversification of electronic recombination within the BaZrO3 band gap. Its optical phenomena are discussed in the light of photoluminescence emission at the green-yellow region around 570 nm. The theoretical model for displaced atoms and/or angular changes leads to the breaking of the local symmetry, which is based on the refined structure provided by Rietveld methodology. For each situation a band structure, charge mapping, and density of states were built and analyzed. X-ray diffraction (XRD) patterns, UV-vis measurements, and field emission scanning electron microscopy (FE-SEM) images are essential for a full evaluation of the crystal structure and morphology.