Interpretation of energy bands of regular quasi-one-dimensional systems in terms of local structure

摘要

A new approach to investigate one-electron spectra of regular quasi-one-dimensional systems is suggested. It is based on an inverted order of operations that differs from the traditional solid-state theory, interchain interactions are taken into account before the intrasubchain ones (subchains correspond here to subsets of translationally equivalent atomic orbitals). The block-diagonalization transformation for matrices [V. Gineityte, Int J Quantum Chem 68, 119 (1998)] is used to perform the first step of the approach. Given that the intersubchain interactions are sufficiently weak, the nonzero blocks of the transformed one-electron Hamiltonian matrix correspond to separate subchains of the initial chain and thereby play the role of effective Hamiltonian matrices for separate energy bands influenced by the interband interaction. Elements of these matrices describe effective interactions between atomic orbitals (AOs) of the given subchain that consist of their direct interactions and of indirect interactions by means of the nearest AOs of other subchains. Moreover, separate additive increments of the dispersion relation depend on particular local effective interactions of AOs. As a result, the approach suggested is especially efficient for interpretation of dispersion curves in terms of local constitution of the system. (C) 2001 John Wiley & Sons, Inc. [References: 32]