Unified quantum mechanical picture for confined spinons in dimerized and frustrated spin S=1/2 chains

A quantum mechanical picture is presented to describe the behavior of confi ned spinons in a variety of S = 1/2 chains. The confinement is due to dimer ization and frustration and it manifests itself as a nonlinear potential V( x) proportional to \x\(b), centered at chain ends (b less than or equal to 1) or produced by modulation kinks (b > 1). The calculation extends to weak or zero frustration some previous ideas valid for spinons in strongly frus trated spin chains. The local magnetization patterns of the confined spinon s are calculated. A (minimum) enhancement of the local moments of about 11/ 3 over a single S = 1/2 is found. Estimates for excitation energies and bin ding lengths are obtained.