Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 61: Correlated Electrons: (General) Theory 2

TT 61.10: Vortrag

Donnerstag, 23. März 2017, 12:00–12:15, HSZ 204

Gridless Stochastic Sampling: Analytic Continuation of Quantum Monte Carlo Data — •Khaldoon Ghanem and Erik Koch — Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich

The stochastic sampling method (StochS) is used for the analytic continuation of quantum Monte Carlo data from the imaginary axis to the real axis. Although StochS does not have explicit parameters, the results depend on the discretization grid which acts as a default model.

To reduce the effect of the grid, we extend StochS into a gridless method (gStochS) by sampling the grid points from a default model instead of having them fixed. The effect of the default model is much reduced in gStochS compared to StochS and depends mainly on its width rather than its shape. The proper width can be then chosen using a simple recipe.

To avoid fixing the width, we go one step further and extend gStochS to sample over a class of default models with different widths. The method is then able to automatically relocate the grid points and concentrate them into the important region. Results show that gStochS gives good results and resolves sharp features in the spectrum without the need for fine tuning a default model.