A1 Refereed original research article in a scientific journal
Electronic transport in molecular junctions: The generalized Kadanoff-Baym ansatz with initial contact and correlations
Authors: Tuovinen Riku, van Leeuwen Robert, Perfetto Enrico, Stefanucci Gianluca
Publisher: AMER INST PHYSICS
Publication year: 2021
Journal:Journal of Chemical Physics
Journal name in sourceJOURNAL OF CHEMICAL PHYSICS
Journal acronym: J CHEM PHYS
Article number: ARTN 094104
Volume: 154
Issue: 9
Number of pages: 12
ISSN: 0021-9606
eISSN: 1089-7690
DOI: https://doi.org/10.1063/5.0040685
Self-archived copy’s web address: https://helda.helsinki.fi/bitstream/handle/10138/328669/JCP20_AR_04994.pdf?sequence=1
Abstract
The generalized Kadanoff-Baym ansatz (GKBA) offers a computationally inexpensive approach to simulate out-of-equilibrium quantum systems within the framework of nonequilibrium Green's functions. For finite systems, the limitation of neglecting initial correlations in the conventional GKBA approach has recently been overcome [Karlsson et al., Phys. Rev. B 98, 115148 (2018)]. However, in the context of quantum transport, the contacted nature of the initial state, i.e., a junction connected to bulk leads, requires a further extension of the GKBA approach. In this work, we lay down a GKBA scheme that includes initial correlations in a partition-free setting. In practice, this means that the equilibration of the initially correlated and contacted molecular junction can be separated from the real-time evolution. The information about the contacted initial state is included in the out-of-equilibrium calculation via explicit evaluation of the memory integral for the embedding self-energy, which can be performed without affecting the computational scaling with the simulation time and system size. We demonstrate the developed method in carbon-based molecular junctions, where we study the role of electron correlations in transient current signatures.
The generalized Kadanoff-Baym ansatz (GKBA) offers a computationally inexpensive approach to simulate out-of-equilibrium quantum systems within the framework of nonequilibrium Green's functions. For finite systems, the limitation of neglecting initial correlations in the conventional GKBA approach has recently been overcome [Karlsson et al., Phys. Rev. B 98, 115148 (2018)]. However, in the context of quantum transport, the contacted nature of the initial state, i.e., a junction connected to bulk leads, requires a further extension of the GKBA approach. In this work, we lay down a GKBA scheme that includes initial correlations in a partition-free setting. In practice, this means that the equilibration of the initially correlated and contacted molecular junction can be separated from the real-time evolution. The information about the contacted initial state is included in the out-of-equilibrium calculation via explicit evaluation of the memory integral for the embedding self-energy, which can be performed without affecting the computational scaling with the simulation time and system size. We demonstrate the developed method in carbon-based molecular junctions, where we study the role of electron correlations in transient current signatures.
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