CLASS OF ANSATZ WAVE-FUNCTIONS FOR ONE-DIMENSIONAL SPIN SYSTEMS AND THEIR RELATION TO THE DENSITY-MATRIX RENORMALIZATION-GROUP

We investigate the density matrix renormalization group (DMRG) discove red by White and show that in the case where the renormalization event ually converges to a fixed point the DMRG ground state can be simply w ritten as a matrix-product form. This ground state can also be rederiv ed through a simple variational ansatz making no reference to the DMRG construction. We also show how to construct the matrix-product states and how to calculate their properties, including the excitation spect rum. This paper provides details of many results announced earlier.