Effect of moving away from half filling on the variational two electron t-U-J interactions on one dimensional even lattices

Abstract

In this study, the two electron interactions on one dimensional (1D) lattices is investigated in a t-U-J model where the t is the kinetic term, the U is the onsite Coulombic term and J is the nearest neighbour (NN) exchange term. Specifically, the effect of moving away from half filling (i.e. when the number of electrons Ne equals the number of sites N) will be investigated by studying N = 4, 6, 8 and 10 in addition to N = 2. The mathematical method to be used is the simplified formulation of the correlated variational approach (CVA) recently developed by us. The ground state energies and the transition points from antiferromagntism to ferromagnetism are obtained for the various sites (N = 2,4,6 8 and 10) and at different values of the onsite interaction strength U/4t and the exchange interaction strength J/4t. It is observed that the energies decrease as one moves away from half filling. The implication of these results is then discussed.

Keywords: ferromagnetism, t-U-J model, variational approach, lattices, half filling

Global Journal of Pure and Applied Sciences Vol. 12(2) 2006: 239-243