DFT+U study of the structural, electronic and optical properties of M1-xPrxF2+x (M= Ca, Ba, x=0.25)

Abstract The aim of this study is to calculate the structural, electronic and optical properties of M1-xPrxF2+x (M=Ba, Ca, x=0.25). The calculations are performed by the spin-polarized density functional theory (DFT) combined with Hubbard U correction method. The band gaps of Ba0.75Pr0.25F2.25 and Ca0.75Pr0.25F2.25are calculated and compared to the binary fluorides BaF2 and CaF2. It is found that the band gaps of the strongly substituted compounds in Praseodymium are smaller than those of the binary materials. The values obtained are 3.21, 2.77, 6.95, 7.14 eV for Ba0.75Pr0.25F2.25,Ca0.75Pr0.25F2.25, BaF2 and CaF2respectively. The comparison between Ba0.75Pr0.25F2.25 and Ca0.75Pr0.25F2.25 is discussed by computing the optical parameters using LSDA and LSDA+U approximations, such as dielectric function, refractive index, reflectivity, absorption, extinction coefficient and energy loss function over a wide range of energy, 0.0-40.0eV.These results would provide a theoretical reference for fundamental science as well as technological application of these compounds.The electronic and optical properties predicted in this work for M1-xPrxF2+x (M=Ba, Ca, x=0.25) may serve as reference for the other experimental and theoretical studies.