Self-consistent GW calculations for single-molecule transport: Bridging the theory-experiment gap in single- molecule transport Kristian S. Thygesen Center for Atomic-scale Materials Design (CAMD) Department of Physics Technical University of Denmark
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Self-consistent GW calculations for single-molecule transport: Bridging the theory-experiment gap in single-molecule transport Kristian S. Thygesen Center.
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Self-consistent GW calculations for single-molecule transport:
Bridging the theory-experiment gap in single-molecule transport
Kristian S. Thygesen
Center for Atomic-scale Materials Design (CAMD)
Department of Physics
Technical University of Denmark
A single molecule
HOMO
LUMO
En
erg
y
)1()( 00 NENE
)1()( 10 NENE
)()1( 00 NENE
)1()( 20 NENE
)()1( 01 NENE
EF EF
HOMO
LUMO
En
erg
y
Closed shell
Weak coupling to electrodes
Chemical bond with electrodesE
nerg
y
EFEF
Finite bias voltageE
nerg
y
EF
EF
En
erg
y
EF
EF
How does electron-electron interactions and the nonequilibrium
conditions affect the electronic structure and transport properties of
molecular junctions?
Finite bias voltage
Outline
DFT Conductance of BDT/BDA junctions
GW-transport scheme
Free molecules
Molecule-solid interface
Finite bias
Example: Engineering molecules for electronics
What happens to the conductance of parent molecules (BDT/BDA) when different functional groups are attached?
DFT-based conductance calculations
Qualitative effect as expected, but…
Effect of side groups very weak, and …
Calculated conductance 10-100 times larger than experimental values!
D. J. Mowbray, G. Jones, and K. S. Thygesen, JCP 128, 111103 (2008)
Effect of side group on HOMO levels
Correction for SI errors and image charge interactions.
Image charge effect partially saves the day for DFT.
D. J. Mowbray, G. Jones, and K. S. Thygesen, JCP 128, 111103 (2008)
Correction for SI errors
Comparison to experiment (BDA@Au)
D. J. Mowbray, G. Jones, and K. S. Thygesen, JCP 128, 111103 (2008)
M. Strange et al., PRL 101, 096804 (2008)
W. H. Thijssen et al. PRL 96, 026806 (2006)
M. Strange, et al. JCP 128, 114714 (2008)
Some success stories
Why does DFT work well in some cases while it fails in other cases?
Beyond the single-particle approximation
Time-dependent DFT Stefanucci and Almbladh, Euro. Phys. Lett. 67, 14 (2004)
Di Ventra and Todorov, J. Phys.:Cond.Mat. 16, 8025 (2004)
Linear response Kubo formulaBokes, Jung and Godby, Phys. Rev. B 76, 125433 (2007)