Electronic structure and surface properties of PrMnO3 (001): A density functional theory study

In this paper, the surface properties of the (001) surface in PrMnO3 are investigated using the projector augmented plane wave (PAW) methods within the spin-polarization generalized gradient approximation (GGA+U), where U is on-site Coulomb interaction correction. The result of the total density of states shows a half-metallic ground state for PrMnO3 in GGA+U treatment. The optimized structure parameters of both cubic and orthorhombic bulk phases are obtained. The electronic properties of the cubic PrMnO3 (001) surface with PrO- and MnO2-terminations are discussed. Based on the results of the calculated surface energies, we predict the surface energies of three low-index surfaces follows the sequence of (001)<(111)<(110). The rumpling for the PrO-terminated surface is much larger than that of the MnO2-terminated surface. Both the PrO- and MnO2-terminated surfaces display a reduction of d12 interlayer distance and an expansion of d23. Bader effective charge of the ion is much smaller than its formal charge which is due to the partial Mn–O bond covalency. The oxygen-vacancy formation energy in bulk PrMnO3 is found to be smaller than other perovskites, e.g. LaMnO3 and SrTiO3. We find that the formation energy of oxygen-vacancy on MnO2-terminated surface is lower than the formation energy of oxygen-vacancy on PrO-terminated surface and Sr-doped PrMnO3 makes oxygen-vacancy formation more easily compared pure PrMnO3.