DYNAMICAL CORRELATIONS IN A HUBBARD CHAIN WITH A RESONATING-VALENCE-BOND GROUND-STATE

Dynamical correlation functions for temperature T = 0 are calculated for a Hubbard chain with infinite on-site repulsion. This chain contains three sites per unit cell and has a known resonating-valence-bond ground state for a filling of two particles per unit cell. A finite system of 24 sites is studied numerically. The recursion method is applied and results for spectral densities are compared to variationally calculated excited-state eigenvalues. Charge and spin degrees of freedom located at the backbone sites are considered. The spectral densities show dispersionless excitations. The energy spectrum displays a gap, indicating an insulating ground state. Spectral functions for the propagation of a single hole in a resonating-valence-bond background are provided and indicate delocalized dispersive hole excitations.