Effects of anharmonicity on nonadiabatic electron transfer: A model

Sina Yeganeh, Mark A Ratner

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The effect of anharmonicity in the intramolecular modes of a model system for exothermic intramolecular nonadiabatic electron transfer is probed by examining the dependence of the transition probability on the exoergicity. The Franck-Condon factor for the Morse potential is written in terms of the Gauss hypergeometric function both for a ground initial state and for the general case, and comparisons are made between the first-order perturbation theory results for transition probability for harmonic and Morse oscillators. These results are verified with quantum dynamical simulations using wave-packet propagations on a numerical grid. The transition-probability expression incorporating a high-frequency quantum mode and low-frequency medium mode is compared for Morse and harmonic oscillators in different temperature ranges and with various coarse-graining treatments of the delta function from the Fermi golden rule expression. We find that significant deviations from the harmonic approximation are expected for even moderately anharmonic quantum modes at large values of exoergicity. The addition of a second quantum mode of opposite displacement negates the anharmonic effect at small energy change, but in the inverted regime a significantly flatter dependence on exoergicity is predicted for anharmonic modes.

Original languageEnglish
Article number044108
JournalJournal of Chemical Physics
Volume124
Issue number4
DOIs
Publication statusPublished - 2006

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electron transfer
Electrons
Morse potential
transition probabilities
Delta functions
Wave packets
harmonic oscillators
oscillators
hypergeometric functions
delta function
wave packets
perturbation theory
grids
low frequencies
deviation
harmonics
Temperature
propagation
approximation
simulation

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Effects of anharmonicity on nonadiabatic electron transfer : A model. / Yeganeh, Sina; Ratner, Mark A.

In: Journal of Chemical Physics, Vol. 124, No. 4, 044108, 2006.

Research output: Contribution to journalArticle

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