TY  - JOUR
A1  - Zenichowski, Karl
A1  - Dokic, Jadranka
A1  - Klamroth, Tillmann
A1  - Saalfrank, Peter
T1  - Current versus temperature-induced switching of a single molecule -  open-system density matrix theory for 1,5-cyclooctadiene on Si(100)
T2  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The switching of single cyclooctadiene molecules chemisorbed on a Si(100) surface between two stable conformations, can be achieved with a scanning tunneling microscope [Nacci , Phys. Rev. B 77, 121405(R) (2008)]. Recently, it was shown by quantum chemical and quantum dynamical simulations that major experimental facts can be explained by a single-mode model with switching enforced by inelastic electron tunneling (IET) excitations and perturbed by vibrational relaxation [Nacci , Nano Lett. 9, 2997 (2009)]. In the present paper, we extend the previous theoretical work in several respects: (1) The model is generalized to a two-mode description in which two C2H4 units of COD can move independently; (2) contributions of dipole and, in addition, (cation and anion) resonance-IET rates are considered; (3) the harmonic-linear vibrational relaxation model used previously is generalized to anharmonic vibrations. While the present models highlight generic aspects of IET-switching between two potential minima, they also rationalize specific experimental findings for COD/Si(100): (1) A single-electron excitation mechanism with a linear dependence of the switching rate on tunneling current I, (2) the capability to switch both at negative and positive sample biases, and (3) a crossover temperature around similar to 60 K from an IET-driven, T-independent atom tunneling regime, to classical over-the-barrier isomerization with exponential T-dependence at higher temperatures for a bias voltage of +1.5 V and an average tunneling current of 0.73 nA.
Y1  - 2012
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36041
SN  - 0021-9606
VL  - 136
IS  - 9
PB  - American Institute of Physics
CY  - Melville
ER  -