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NEGF‐HF Method in Molecular Junction Property Calculations
Author(s) -
GALPERIN MICHAEL,
NITZAN ABRAHAM
Publication year - 2003
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1292.003
Subject(s) - voltage drop , asymmetry , electron , formalism (music) , condensed matter physics , quantum , voltage , chemistry , electron transport chain , polarity (international relations) , physics , quantum mechanics , art , musical , biochemistry , visual arts , cell
A bstract : Electron‐electron interaction is an essential issue in predicting the properties of a molecular conduction junction. An accurate treatment requires taking proper account of the potential distribution across the junction as well as for the change in electronic structure under the external voltage drop. Another important point is the necessity to treat molecules as open quantum systems. In this paper we address these issues within the framework of the non‐equilibrium Green's function formalism at the Hartree‐Fock level (NEGF‐HF), which permits a self‐consistent treatment of the problem. We apply the method to study the experimentally observed asymmetry in the I‐V curves with respect to polarity of voltage bias in Hg‐Au junctions containing bilayers of alkanethiols of various chain lengths. The origin of the effect is suggested to be the asymmetric behavior of the character of the highest occupied molecular orbital (HOMO) of the junction at opposite biases, which leads to different effective barriers for electron transfer across the junction at opposite signs of the voltage drop. The calculated potential profile shows the capacitor‐like nature for the junction with the weak link.