Abstract
The structural and electronic properties of the cubic fluoroperoveskite and have been investigated using the full-potential-linearized augmented plane wave method within the density functional theory. The exchange-correlation potential was treated with the local density approximation and the generalized gradient approximation. The calculations of the electronic band structures show that has an indirect bandgap, whereas has a direct bandgap. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the effect of pressure and temperature on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and the heat capacity for and compounds are investigated for the first time.