Dynamical properties of the one-dimensional supersymmetric t-J model: A view from elementary excitations

Dynamical properties, such as dynamical spin and charge structure factors a nd single-particle spectral functions, are studied for the one-dimensional supersymmetric t-J model with inverse-square interaction. Exact diagonaliza tion and the recursion method are used for finite systems up to 16 sites. A simple rule is proposed to understand the supermultiplet structure in the excitation spectrum. Numerical calculations show that the dynamical spin st ructure factor is independent of the electron density in the region where o nly two spinons contribute. In the electron removal spectrum from half-fill ing, close correspondence is found between the dominant contribution from t hree-spinon plus one-holon states in the t-J model and the two-spinon excit ations in the Haldane-Shastry model. Comparison is made with dynamics of th e nearest-neighbor supersymmetric t-J model.