Electric Field Gradients (EFGs) Calculations in UX2(X=Bi, Sb) Compounds

In this paper، electronic properties of anti-ferromagnetic UX2 (X=Bi، Sb) compounds were investigated by ab initio calculations based on the density functional theory (DFT)، using the augmented plane waves plus the local orbitals (APW+lo) method. To calculate the exchange-correlation function، we used the LDA، GGA، LDA+U and GGA+U schemes as well as the exact exchange for the correlated electrons (EECE) scheme. The electric field gradients (EFGs) for UX2 compound at the site of uranium atom was calculated and compared with the experimental values. The EFGs for UBi2 crystal was smaller than that of USb2 crystal due to the difference between their magnetic structures. The EFGs for UBi2 were found to be in better agreement with the experiment within the EECE method than the other used methods.