State Representation Approach for Atomistic Time-Dependent Transport Calculations in Molecular Junctions

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• 作者：Tamar Zelovich ; Leeor Kronik ; Oded Hod
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2014
• 出版时间：August 12, 2014
• 年：2014
• 卷：10
• 期：8
• 页码：2927-2941
• 全文大小：523K
• ISSN：1549-9626

文摘

We propose a new method for simulating electron dynamics in open quantum systems out of equilibrium, using a finite atomistic model. The proposed method is motivated by the intuitive and practical nature of the driven Liouville鈥搗on-Neumann equation approach of S谩nchez et al. [J. Chem. Phys. 2006, 124, 214708] and Subotnik et al. [J. Chem. Phys. 2009, 130, 144105]. A key ingredient of our approach is a transformation of the Hamiltonian matrix from an atomistic to a state representation of the molecular junction. This allows us to uniquely define the bias voltage across the system while maintaining a proper thermal electronic distribution within the finite lead models. Furthermore, it allows us to investigate complex molecular junctions, including multilead configurations. A heuristic derivation of our working equation leads to explicit expressions for the damping and driving terms, which serve as appropriate electron sources and sinks that effectively 鈥渙pen鈥?the finite model system. Although the method does not forbid it, in practice we find neither violation of Pauli鈥檚 exclusion principles nor deviation from density matrix positivity throughout our numerical simulations of various tight-binding model systems. We believe that the new approach offers a practical and physically sound route for performing atomistic time-dependent transport calculations in realistic molecular junction models.