Correct Density Functional Theory Description of Electronic Properties of Cadmium Sulfide and Ferroelectric Sodium Nitrite

We present calculated, electronic and related properties of wurtzite cadmium sulfide (w-CdS), zinc blende cadmium sulfide (zb-CdS) and ferroelectric sodium nitrite (ferro-NaNO2). Our first principle, ground state, ab-initio, non-relativistic calculations employed a local density functional approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). Following the Bagayoko, Zhao, and Williams (BZW) method, we solved self-consistently both the Kohn-Sham equation and the equation giving the ground state density in terms of the wave functions of the occupied states. We provide detailed computational results on the electronic energy bands, the atomic wavefunctions, the density of states, the partial density of states and the electronic effective masses. Our results compared favorably with experimental measurements, with a superior agreement than any other theoretical calculation known to us. Our calculated, direct band gaps for w-CdS are 2.47, 2.48 and 2.52 eV, at the G point; the direct band gap for zb-CdS at the G point is 2.39 eV. We found an indirect band gap of 2.83 eV and direct band gap of 3.22 eV at the G point for ferro-NaNO2. These results are in excellent agreement with experiments. So are the calculated density of states and the electron effective mass.