Non-orthogonal orbitals for localized electrons III. Application to periodic one dimensional lattices Original Research Article

A new hybrid method associating an effective spin hamiltonian with an approximate spin function is applied to an infinite s=1/2 magnetic chain. The effective spin hamiltonian is derived from the single configuration spin-coupled valence bond wave function built upon weakly overlapping non-orthogonal orbitals. The approximate spin function gives a zeroth order description of the short range spin correlation while insuring a proper translational symmetry. The variationally optimized magnetic coupling integrals are extracted using the long range Pariser–Parr–Pople model and the influence of the exchange and Coulomb interactions cut off is shown.