Variational Cluster Approximation combined with Dynamical Density-Matrix Renormalization Group Method

摘要

Motivated by the recent progress [1] of the variational cluster approximation method (VCA [2]) based on the self-energy functional theory (SFT [3]), we use the dynamical density-matrix renormalization group method (DDMRG [4]) to compute the Green's function of variational cluster. We rst apply this approach to the one-dimensional Hub-bard model. We then discuss the size dependence of the variational cluster, and compare our results with another method including Bethe ansatz solution, and direct calculation using DDMRG. Next, we calculate the staggered magnetic moment in the weakly coupled one-dimensional Hubbard chains. The calculation results are compared with the results of quantum Monte Carlo method for the weakly coupled one-dimensional Heisen-berg model [5]. We also present the one-particle excitation spectra for the weakly coupled one-dimensional Hubbard model at half- lling, and discuss the crossover from the excitation characterized by the spin-charge separation to the dispersion of the antiferromagnetic state.