Toward a systematic $1/d$ expansion: Two-particle properties

We present a procedure to calculate $1/d$ corrections to two-particle properties around the infinite-dimensional dynamical mean-field limit. Our method is based on a modified version of the scheme of Schiller and Ingersent (Ref. 7), where the cancellation of overcounted diagrams is assured at each iteration step. We test our method on the half-filled Hubbard model using the fluctuation exchange approximation. To within numerical accuracy, we find stable, causal solutions for which $1/d$ corrections to the local correction are relatively small.