Flat histogram diagrammatic Monte Carlo method: Calculation of the Green’s function in imaginary time

摘要

The diagrammatic Monte Carlo (DiagMC) method is a numerical technique which samples the entirendiagrammatic series of the Green’s function in quantum many-body systems. In this work, we incorporatenthe flat histogram principle in the diagrammatic Monte Carlo method, and we term the improved version the “flatnhistogram diagrammatic Monte Carlo” method.We demonstrate the superiority of this method over the standardnDiagMC in extracting the long-imaginary-time behavior of the Green’s function, without incorporating any anpriori knowledge about this function, by applying the technique to the polaron problem.