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First principles calculations, using Full Potential Linearized Augmented Plane Wave (FP-LAPW) method within the framework of density functional theory (DFT), are used to study structural, electronic and optical properties of barium zirconate (BaZrO3) in its pristine and intrinsic vacancy defects using the supercell approach. The calculated structural parameters with four semi-local exchange-correlation functionals Local Density Approximation (LDA), Generalized Gradient Approximation (GGA), Perdew–Burke–Ernzerhof for solids (PBEsol) GGA, Wu and Cohen (WC) GGA includes, lattice parameter ao, ground state volume Vo, bulk modulus Bo, total energies Eo, and bond lengths of Ba, Zr and O atoms. Furthermore, to avoid the underestimation of the band profile by other DFT schemes we highlight the LDA plus modified Becke–Johnson (mBJ) potential in lieu of attaining opto-electronic aspects close to the anticipated experimental findings. The computed electronic band gap shows that band profile remains indirect with small difference in detail. The optical properties of Ba, Zr and O vacancy containing 2 × 2 × 2 supercells of BaZrO3 are calculated using real and imaginary part of dielectric function. The real part of the dielectric function using mBJ_s modification reveals that static dielectric constant of BaZrO3 is 3.8 that is, in excellent agreement with the experimental value of 4.0. The structural, electronic and optical properties of pristine BaZrO3 along with its non-stoichiometric intrinsic vacancy containing forms are studied to provide experimentalist with a better understanding of its physical properties which are vital for its functional utilization.

Density functional theory is used to explore structural, elastic, and mechanical properties of SrLiF3, SrNaF3, SrKF3 and SrRbF3 fluoroperovskite compounds by means of an ab-initio Full Potential-Linearized Augmented Plane Wave (FP-LAPW) method. Several lattice parameters are employed to obtain accurate equilibrium volume (Vo). The resultant quantities include ground state energy, elastic constants, shear modulus, bulk modulus, young's modulus, cauchy's pressure, poisson's ratio, shear constant, ratio of elastic anisotropy factor, kleinman's parameter, melting temperature, and lame's coefficient. The calculated structural parameters via DFT as well as analytical methods are found to be consistent with experimental findings. Chemical bonding is used to investigate corresponding chemical trends which authenticate combination of covalent-ionic behavior. Furthermore electron density plots as well as elastic and mechanical properties are reported for the first time which reveals that fluorine based strontium series of perovskites are mechanically stable and posses weak resistance towards shear deformation as compared to resistance towards unidirectional compression while brittleness and ionic behavior is dominated in them which decreases from SrLiF3 to SrRbF3. Calculated cauchy's pressure, poisson's ratio and B/G ratio also proves ionic nature in these compounds. The present methodology represents an effective and influential approach to calculate the whole set of elastic and mechanical parameters which would support to understand various physical phenomena and empower device engineers for implementing these materials in numerous applications.

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