Kernel polynomial representation for imaginary-time Green’s functions in continuous-time quantum Monte Carlo impurity solver
Huang Li†,
       

Typical integral kernel functions fn used to improve the quality of the polynomial expansion series. The order of expansion series is fixed to N = 64. The Dirichlet, Jackson, and Fejér kernels take no parameters. For the Lorentz kernel, the λ parameter is fixed at 1.0. For the Wang–Zunger kernel, parameters α and β are 1.0 and 4.0, respectively.