Perpustakaan Digital ITB

The electronic structures of distorted perovskite CaFeO3 and YNiO3 have been studied using a Periodic Approach of Unrestricted Hartree-Fock, Local Den- sity Approximation, and hybrid Density Functional Theory. The calculation methods are implemented in the CRYSTAL06 program package. We observe di?erent magnitude of band gap obtained with the methods. UHF and B3LYP functional of DFT give correct insulating behavior with band gap of about 10 eV and 1 eV, respectively, while Local Density Approximation gives metallic character. Moreover, the calculated charges using all methods are di?erent for CaFeO3 and YNiO3 compounds in the distinct TM sites. However, the di?erence of about 0.07 is much smaller than the simple ionic prediction of charge disproportionation. The charge and spin density of states obtained in this calculation is used to determine the band gap, the total charge and total spin density of the transition metal on di?erent sites in these perovskites.