Improved Treatment of Frequency Sums in Propagator-Renormalized   Perturbation Theories
  We present a massively parallel algorithm for calculating the self-energy in self-consistent finite temperature perturbation theory for lattice models. The algorithm uses analytic functions with appropriate asymptotic high frequency behavior and fast Fourier transforms to accurately calculate the self-energy at low-frequency. Traditional methods that truncate the high frequency tails of the temperature Green's function lead to `contamination' of the low-frequency behavior of the self-energy. Our algorithm is both accurate and scalable. We compare results for the Hubbard model using various techniques for handling the high frequency tails of the temperature Green's function. 
J.J. Deisz (1), D.W. Hess (2), and J.W. Serene (1) ((1) Department of   Physics, Georgetown University (2) Complex Systems T...