A microscopic approach to the dimerization in frustrated spin-1/2 antiferromagnetic chains

摘要: The spontaneous dimerization of frustrated spin- 1/2 antiferromagnetic chains is studied via a microscopic approach based on proper set composite operators (i.e., pseudo-spin operators). Two approximation schemes are developed. Firstly, spin-wave made Dyson-Maleev-like boson transformation. ground-state properties and the triplet excitation spectra obtained as functions coupling parameter. Secondly, treatment, operators, formulated within framework powerful, systematic coupled-cluster method (CCM). Comparison between various approximations made. advantage CCM for purposes improvement emphasized.