Structural properties and the reaction mechanism. Calcium perovskite oxides with the general formula of CaMO 3 crystallize in the Pnma space group, where each oxygen atom is shared between two transition metal (M) ions, each coordinated octahedrally (Fig. ). This arrangement induces a crystal field effect, resulting in the splitting of the transition metal 3d orbitals into three lowerenergy t 2g orbitals and two higher-energy e g orbitals . The e g orbitals overlap with the oxygen p orbitals to form σ bonds, while the t 2g orbitals engage in π bonding interactions. A threedimensional integration of these states produces a density of states (DOS) diagram, providing a detailed representation of the electronic density associated with each orbital state.