RENORMALIZATION-GROUP ACCELERATION OF SELF-CONSISTENT-FIELD SOLUTIONS- 2-DIMENSIONAL HUBBARD-MODEL

Momentum- and frequency-dependent self-consistent field theories provi de a potentially powerful tool for analyzing condensed-matter models f or interacting electrons. Such theories generally require the solution of multidimensional integral equations. Solutions are limited by dema nds on computational time and storage, which increase rapidly for calc ulation of low-temperature properties. A renormalization-group techniq ue which allows the sequential elimination of regions of high frequenc y and momentum is presented in detail, and is then applied to the solu tion of the fluctuation exchange approximation for the two-dimensional Hubbard model. Effective meshes with as many as 10(4) frequencies and 512(2) k points can be analyzed on a vector supercomputer using this approach. As a sample application, it is demonstrated that the fluctua tion exchange approximation exhibits non-Fermi liquid behavior near ha lf filling for sufficiently large interaction strengths.