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RESEARCH PRODUCT
Charge dynamics in molecular junctions: nonequilibrium Green's function approach made fast
Simone LatiniGianluca StefanucciEnrico PerfettoR. Van LeeuwenA.-m. Uimonensubject
Propagation timeWork (thermodynamics)SpeedupCondensed Matter - Mesoscale and Nanoscale Physicsta114Computer sciencePropagatorFOS: Physical sciencesNanotechnologyFunction (mathematics)Condensed Matter PhysicsElectronic Optical and Magnetic MaterialsSettore FIS/03 - Fisica della Materiasymbols.namesakeGreen's functionMesoscale and Nanoscale Physics (cond-mat.mes-hall)symbolsStatistical physicsQuantumAnsatzdescription
Real-time Green's function simulations of molecular junctions (open quantum systems) are typically performed by solving the Kadanoff-Baym equations (KBE). The KBE, however, impose a serious limitation on the maximum propagation time due to the large memory storage needed. In this work we propose a simplified Green's function approach based on the Generalized Kadanoff-Baym Ansatz (GKBA) to overcome the KBE limitation on time, significantly speed up the calculations, and yet stay close to the KBE results. This is achieved through a twofold advance: first we show how to make the GKBA work in open systems and then construct a suitable quasi-particle propagator that includes correlation effects in a diagrammatic fashion. We also provide evidence that our GKBA scheme, although already in good agreement with the KBE approach, can be further improved without increasing the computational cost.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2014-01-01 |