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Electric field effects on the octanedithiol wire
Author(s) -
Li Jun,
Tomfohr John K.,
Sankey Otto F.
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200303233
Subject(s) - hamiltonian (control theory) , electric field , atomic orbital , chemistry , molecule , diagonal , molecular orbital , density functional theory , molecular wire , molecular physics , atomic physics , computational chemistry , physics , quantum mechanics , geometry , mathematical optimization , mathematics , electron , organic chemistry
We theoretically study the electric field profile and the voltage profile across a model molecule in a metal‐molecule‐metal junction under bias. The model system is octanedithiol (S–(CH 2 ) 8 –S) sandwiched between two gold electrodes (Au[111]). We use a simple, but approximate, method to investigate the voltage profile across the molecule and the change of electronic states under a given bias. The key simplification is to artificially shift the two metal (Au) Hamiltonians relative to each other within a closed system to simulate the external bias of an open system. The Hamiltonian of the closed system is calculated within density functional theory using local orbitals and the electronic structure of the entire system is determined self‐consistently. In the final step after charge transfer has taken place, we remove the artificial metal Hamiltonian shifts to reveal an oppositely biased system with a built‐in electric field across the molecule. The electric field effects on the electronic structure of the molecule are analyzed by tracking the on‐site orbital energies (diagonal Hamiltonian matrix elements) and the projected electronic density of states onto atoms along the molecular wire. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)