A DFT study to explore structural, elastic, mechanical, phonon, electronic and optical properties of halide perovskites AgXF3(X=Be,Ca)$$ {\mathrm{AgXF}}_3\left(\mathrm{X}=\mathrm{Be},\mathrm{Ca}\right) $$ with PBEsol, TB‐mBJ and SCAN functionals

First principles calculations have been performed using full potential linearized augmented plane wave, FP‐LAPW, within Wien2k to elucidate structural, elastic, mechanical, phonon, electronic and optical properties of lead free halide perovskites AgXF3(X=Be,Ca)$$ {\mathrm{AgXF}}_3\left(\mathrm{X}=\mathrm{Be},\mathrm{Ca}\right) $$. The energy volume curve fitting is used to examine structural stability. For structural optimization and mechanical properties, we employed Perdew–Burke–Ernzerhof generalized gradient approximation and PBEsol, revised for solids, exchange and correlation functional. The optimized lattice constant of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ is 3.631 and 4.349Å. The elastic constant C11$$ {\mathrm{C}}_{11} $$, C12$$ {\mathrm{C}}_{12} $$ and C44$$ {\mathrm{C}}_{44} $$ are computed to extract different mechanical parameters like Poisson's ratio, Pugh's ratio, bulk modulus, shear modulus, Young's modulus, anisotropic ratio, Cauchy pressure and shear constant. The mechanical parameters exhibit greater structural, mechanical and dynamical stability of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ than AgCaF3$$ {\mathrm{AgCaF}}_3 $$. The electronic and optical properties are calculated by using TB‐mBJ and SCAN potentials in addition to PBEsol. The electronic band gap of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ is 4.71 and 6.01 eV with TB‐mBJ and both perovskites are indirect band gap materials. The optical response of these perovskites against wide range of incident electromagnetic radiation is assessed by calculating absorption, reflection, optical conductivity, dielectric constant, energy loss function and refraction. Strong absorption, high optical conductivity and low reflectivity indicates that AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ are promising materials for photovoltaic applications. [ABSTRACT FROM AUTHOR]