Theoretical Study of Spin Alignment of Organic High-Spin Molecules in Terms of VB Description

Abstract

Abstract Spin alignment in organic high-spin molecules and their topological isomers with both unpaired π and [sgrave] electrons has been studied by the exact numerical solutions of the valence-bond Heisenberg Hamiltonian and of the UHF calculation of the generalized Hubbard Hamiltonian. In order to clarify the main path-way of the spin correlation, the spin configurations with large coefficients have been extracted from the eigenfunctions in the ground and low-lying excited states of the Heisenberg Hamiltonian. The contributions of their spin configurations to the total spin energy have been calculated. Using this procedure, important spin configurations (important path-way of exchange correlations) of the ground and low-lying excited states have been clarified. A similar treatment can be carried out by the generalized Hubbard Hamiltonian. Thus, the VB decompositions of UHF solutions of the generalized Hubbard model have been carried out using the total α spin and total β spin densities on each carbon si...