Flow-equations for Hamiltonians

摘要: Flow-equations are introduced in order to bring Hamiltonians closer diagonalization. It is characteristic for these equations that matrix-elements between degenerate or almost states do not decay very slowly. In understand different types of physical systems this framework it probably necessary classify various degeneracies and investigate the corresponding behavior. In general generate many-particle interactions. However, an n-orbital model two-particle interaction closed limit large n. Solutions a one-dimensional considered. There appear convergency problems, which removed, if instead diagonalization only block-diagonalization into blocks with same number quasiparticles performed.