Dual current anomalies and quantum transport within extended reservoir simulations
Autor: | Michael Zwolak, Marek M. Rams, Gabriela Wójtowicz, Justin E. Elenewski |
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Rok vydání: | 2021 |
Předmět: |
Physics
Strongly Correlated Electrons (cond-mat.str-el) Condensed Matter - Mesoscale and Nanoscale Physics Discretization Scattering FOS: Physical sciences Conductance Condensed Matter - Strongly Correlated Electrons Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Convergence (routing) Density of states Relaxation (physics) Tensor Statistical physics Current (fluid) |
Zdroj: | Physical Review B. 104 |
ISSN: | 2469-9969 2469-9950 |
Popis: | Quantum transport simulations are rapidly evolving and now encompass well-controlled tensor network techniques for many-body limits. One powerful approach combines matrix product states with extended reservoirs. In this method, continuous reservoirs are represented by explicit, discretized counterparts and a chemical potential or temperature drop is maintained by external relaxation. Currents are strongly influenced by relaxation when it is very weak or strong, resulting in a simulation analog of Kramers' turnover for solution-phase chemical reactions. At intermediate relaxation, the intrinsic conductance, that given by the Landauer or Meir-Wingreen expressions, moderates the current. We demonstrate that strong impurity scattering (i.e., a small steady-state current) reveals anomalous transport regimes within this methodology at weak-to-moderate and moderate-to-strong relaxation. The former is due to virtual transitions and the latter to unphysical broadening of the populated density of states. Thus, the turnover analog has $five$ standard transport regimes, further constraining the parameters that lead to recovery of the intrinsic conductance. In the worst case, the common strategy of choosing a relaxation strength proportional to the reservoir level spacing can prevent convergence to the continuum limit. This advocates a simulation strategy where one utilizes the current versus relaxation turnover profiles to identify simulation parameters that most efficiently reproduce the intrinsic physical behavior. 16 pages, 5 figures |
Databáze: | OpenAIRE |
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