摘要:

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 site in the UHF total wavefunction. The VB picture so obtained is also qualitatively in agreement with the results of the valence-bond Heisenberg Hamiltonian. The detailed mechanism in the spin alignment has been discussed in terms of the VB description by these two model Hamiltonian approaches.

ISSN:1058-725X    

DOI:10.1080/10587259508034053

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:1058-725X    

DOI:10.1080/10587259508034032

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor