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arXiv · 1202.5814

Benchmark of a modified Iterated Perturbation Theory approach on the 3d FCC lattice at strong coupling

Louis-Francois Arsenault·Patrick Semon·A. -M. S. Tremblay
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Abstract

The Dynamical Mean-Field theory (DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact Continuous-Time Quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy and specific heat on the FCC lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. Several algorithms that speed up the calculations are described in appendices.

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Louis-Francois Arsenault, Patrick Semon, A. -M. S. Tremblay. 2012-02-27. Benchmark of a modified Iterated Perturbation Theory approach on the 3d FCC lattice at strong coupling. https://doi.org/10.1103/physrevb.86.085133

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