1. Applicability of the wide-band limit in DFT-based molecular transport calculations
- Author
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Johannes S. Seldenthuis, C. J. O. Verzijl, and J. M. Thijssen
- Subjects
Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,ab initio calculations ,Ab initio ,General Physics and Astronomy ,FOS: Physical sciences ,Function (mathematics) ,Functional imaging [IGMD 1] ,Computational physics ,Green's function methods ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Molecular Transport ,Molecule ,Wide band ,Limit (mathematics) ,Physical and Theoretical Chemistry ,Ground state ,approximation theory ,Voltage drop ,density functional theory - Abstract
Item does not contain fulltext Transport properties of molecular junctions are notoriously expensive to calculate with ab initio methods, primarily due to the semi-infinite electrodes. This has led to the introduction of different approximation schemes for the electrodes. For the most popular metals used in experiments, such as gold, the wide-band limit (WBL) is a particularly efficient choice. In this paper, we investigate the performance of different WBL schemes relative to more sophisticated approaches including the fully self-consistent non-equilibrium Green's function method. We find reasonably good agreement between all schemes for systems in which the molecule (and not the metal-molecule interface) dominates the transport properties. Moreover, our implementation of the WBL requires negligible computational effort compared to the ground-state density-functional theory calculation of a molecular junction. We also present a new approximate but efficient scheme for calculating transport with a finite bias. Provided the voltage drop occurs primarily inside the molecule, this method provides results in reasonable agreement with fully self-consistent calculations.
- Published
- 2013