Local approach study of electron correlation effects in the Hubbard model

ARMEN N. KOCHARIAN, P. S. Ovnanyan

那由多 竹森, Nayuta Takemori, 昌久 古賀 +1 more

Guozhu Wei, NIE HUI-QUAN, Kaiyi Zhang +1 more

Based on the intraatomic electron correlation and the interatomic electron and spin correlation, the local approach has been used to the Hubbard model. The term〈OOH〉which was neglected in the general calculation is retained in our calculation. Camparing our results with those of the general calculation, we find that when U is large, the effects of the term〈OOH〉in the paramagnetic phase can not be heglected for calculating the correlation energy, the ground state energy, the local moments and the antiferromagnetic polarization around the local moments. To estimate more accurately the electron correlation effects, one has to calculate to higher orders and check he convergency of the series.

Arisato Kawabata

G. Z. Wel, H. Q. Nie, K. Y. Zhang

Abstract Using series expansion of local approach, the electron coupling between nearest‐neighbour sites is considered to investigate the electron correlation effect in the Hubbard model. The results show that when the off‐diagonal elements of the density matrix are considered in the calculation, it leads to an enhancement of double occupancy and are duce of the formation of the local moments.

D.K. Ghosh