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

Table 1

Structural properties of the simple cubic perovskite phase of NaNbO₃ in comparison to experimental data.

	PBE	PBEsol	AM05	PBE0	Experiment
a (Å)	3.975	3.944	3.947	3.931	3.9507 [28]
(Å^3)	62.807	61.349	61.490	60.745	61.6626 [28]
(GPa)	176.6	188.8	185.6	204.0	136.7^a
					193.02 [15], 206.3^b
(GPa)	4.4	4.6	4.6	4.3	—
(eV)	2.404	2.386	2.383	4.567	—
(eV)	1.652	1.639	1.642	3.756	3.29 [34]

Given are the lattice parameter a, equilibrium unit-cell volume , the bulk modulus and its pressure derivative , and the direct (-) and indirect (M-) Kohn–Sham energy gaps, respectively, calculated with different exchange-correlation functionals. ^aCalculated from experimental elastic constants  GPa and  GPa [11] using (4); ^bcalculated from theoretical elastic constants  GPa and  GPa [13] using (4).