SPIN CONFIGURATIONS OF π ELECTRONS AND DIMERIZATION IN QUASI-ONE-DIMENSIONAL ORGANIC BIPARTITE LOZENGE CHAINS

Based on a theoretical model proposed for an organic bipartite lozenge ferrimagnetic chain, the spin configuration of π electrons and the dimerization are investigated. With the Hartree–Fock approximation, the strong electron–phonon coupling and the electron–electron interaction in the one-dimensional system are taken into account self-consistently. It is shown that around the middle of the chain appears a π electron spin polarization cloud with alternation of sign and amplitude of the spin density extending over a certain distance, which extends all over the chain with no decay when the e–e interaction is larger than a critical value. In the stable ferrimagnetic state, the antiferromagnetic exchange interaction between electrons at site A and site B along the chain will become very strong, and almost zero dimerization happens for the chain.

How Strong is the Electron Correlation in Conjugated Polymers

ABSTRACTCorrelation effects on the band gap are studied to get the strength of electron interactions in conjugated polymers. In the presence of an additional electron or hole, the correlation induces a polarization cloud around the additional particle, which forms a polaron. For the excitation energy of a polaron, there is a competition between a loss of correlation energy in the ground state and a gain of polarization energy due to the scattering through the additional particle. The calculation has been done both for the Hubbard Model and long-range interactions. For polyacetylene, we obtain the on-site repulsion U = 4.4 eV and the nearest-neighbor interaction V = 0.8 eV. The polarization effect of Σ electrons and theoretical results on the effective interaction are discussed. The strength of effective interactions should depends on physical processes.

Faddeev Equations in the Functional Quantum Theory of the Non-Linear Spinorfield

Starting with a linear partial differential operator for a certain system of transition amplitudes associated to a state |a> with baryon number ρ(a) we derive an equation in the ρ(a)-sector of the Functional space which provides the state |a> with an effective potential caused by the polarization cloud. With regard to the needs of n-body scattering we then undertake a cluster decomposition of the effective potential. In particular, we derive the relativistic analoga of Lippmann-Schwinger-and Faddeev equations.