The Coulomb interaction and volume compress effect on spin and orbital moment of NiO

The Couloumb interaction U and volume compress (VC) effect on the spin and orbital moment of NiO at temperature 523 K have been calculated using the linear muffin-tin orbital (LMTO) method. The results show the lattice constant decrease from 4.19 to 2.45 A¿ with increasing of volume compress from 0 to 80%. When the VC fixed, the both spin and orbital moment of Ni²⁺ ion gradually increase to 1.87 ¿_B and 0.17 ¿_B, respectively with increasing of Coulomb interaction U from 0 eV to 10.0 eV. On other hand, when U fixed and VC is varied from 0% to 80%, the spin moment slightly decrease and then rapidly decrease to 0 ¿_B, while the orbital moment dramatically decrease to 0 ¿_B.