Study on the ferrimagnetic ground state of a phenylene molecule chain

The properties of the ferrimagnetic ground state of an m  -phenylene molecule chain are studied with the Hubbard model. Within mean-field theory, the ferrimagnetic ground state with a total spin S=1S=1 per unit cell is obtained. The result shows that if the on-site electron–electron repulsion U   at the radical sites and U0U0 at the phenylene ring sites are different, the energy gap may disappear and the ferrimagnetic ground state becomes unstable. The spin configuration exhibits that the ferrimagnetic ground state results from the antiferromagnetic correlations between the nearest neighbors. Due to the cooperation and competition between the hopping integral and the on-site repulsion at different sites, the charge density and spin density can transfer between the radical sites and the phenylene ring sites.