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Current-induced heating and cooling in molecular junctions

Thursday, September 28, 2017 - 12:00
Donostia International Physics Center
Giuseppe Foti (Institute of Physics, Czech Academy of Science, Prague)
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The delicate
balance between heat generation and dissipation in molecular junctions subject
to an external bias is strongly influenced by the electronic structure of the
metal-molecule-metal system.

The presence of
sharp molecular resonances close to the Fermi window can, in fact, favor the
transfer of energy from molecular vibrations to the electrodes or, on the other
hand, promote the efficient emission of localized vibrational quanta with
important implications for the stability of the junction [1,2].

In this talk I
will present our first principles calculations based on density
functional theory (DFT) in combination with the nonequilibrium Green's function
formalism (NEGF) addressing the important role of the electronic structure in
the heating and cooling dynamics (HCD) of molecular junctions under an applied

I will show how
the atomistic details of electrode terminations as well as the presence of
contaminants adsorbed nearby the junction can lead to qualitatively different
HCD of N-heterocyclic carbenes (NHCs) under an applied bias [3, 4]. Also, I
will present our recent efforts in understanding the origin of vibrational
instabilities in molecular wires with broken conjugation.

[1] J.-T. Lü, P. Hedegård, and M.
Brandbyge, Phys. Rev. Lett. 107, 046801 (2011)

[2] M. Engelund, J. A. Fürst, A. P. Jauho,
and M. Brandbyge Phys. Rev. Lett. 104, 036807 (2010)

[3] G. Foti and H. Vázquez, J. Phys. Chem.
C 121, 1082 (2017)

[4] G. Foti and H. Vázquez, Beilstein J.
Nanotechnol. (accepted)

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