TY - JOUR
T1 - NEGF-HF Method in Molecular Junction Property Calculations
AU - Galperin, Michael
AU - Nitzan, Abraham
PY - 2003/12
Y1 - 2003/12
N2 - 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.
AB - 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.
KW - Molecular capacitors
KW - Molecular electronics
KW - Nonequilibrium Green's function
KW - Rectification
UR - http://www.scopus.com/inward/record.url?scp=0347320481&partnerID=8YFLogxK
U2 - 10.1196/annals.1292.003
DO - 10.1196/annals.1292.003
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AN - SCOPUS:0347320481
SN - 0077-8923
VL - 1006
SP - 48
EP - 67
JO - Annals of the New York Academy of Sciences
JF - Annals of the New York Academy of Sciences
ER -