First-principles study on the structural, elastic, electronic, optical and thermophysical properties of NaNO3 and K-doped NaNO3

The current work illustrates the optical, thermophysical, electronic, elastic, and structural characteristics of pure and K-doped NaNO3 obtained using DFT calculations. Electronic characteristics such as band structure, projected and total density of states of pure and doped NaNO3 are analyzed where the calculated band gaps for pure and K-doped NaNO3 were discovered to be 3.05 eV and 2.90 eV, respectively. The Berry-phase calculations carried out on both systems showed the existence of ferroelectric polarization, where an enhanced spontaneous polarization value of 36 mu C/cm(2) for K-doped NaNO3, as compared to 20 mu C/cm(2) for intrinsic NaNO3 is obtained. The thermophysical properties such as bulk modulus (B-0), Debye temperature (theta(D)), and specific heat capacity (C-v) were calculated over a wide temperature range from 0 K to 800 K. The linear optical properties namely the dielectric constant, refractive index, electron energy loss function, absorption and extinction coefficient are calculated in wide energy range from 0 to 30 eV and discussed in detail.