Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study

Figure 2

NaNbO₃ total energy curves calculated with different exchange-correlation functionals for (a) the rhombohedral phase (SG 161), (b) the orthorhombic phase (SG 57), (c) the monoclinic phase (SG 6), and (d) the simple cubic perovskite phase (SG 221). Exchange-correlation functionals include the conventional PBE functional of Perdew et al. [16], the PBEsol functional revised for solids [18], the AM05 functional [17], and the PBE0 hybrid functional [19]. Zero energy has been rescaled corresponding to the lowest energy for each functional. The vertical black dashed lines correspond to the experimental ground state volumes.