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Projekt Druckansicht

Zustandsselektive Chemie und Quantendynamik polyatomarer Reaktionen

Antragsteller Professor Dr. Uwe Manthe
Fachliche Zuordnung Theoretische Chemie: Elektronenstruktur, Dynamik, Simulation
Förderung Förderung von 2014 bis 2021
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 261376728
 
Erstellungsjahr 2021

Zusammenfassung der Projektergebnisse

The project investigated the dynamics of polyatomic reactions on a detailed quantum stateresolved level. Reactions of methane with atoms and diatoms were studied. These reactions are important processes in atmospheric and combustion chemistry as well as prototypical examples of polyatomic reaction processes intensively studied in fundamentally oriented research. Accurate first principles-based quantum theory was successfully employed to investigate the reaction dynamics in detail. Correlations between the quantum states of the reactants and products in a six atom reaction were studied for the first time by rigorous full-dimensional quantum dynamics calculations. The calculations demonstrated the crucial importance of the transition state for the modespecific chemistry observed in these reactions. The quantum state distribution of the reaction products is determined by the geometry of the effective transition state. For the H+CH4 → H2 +CH3 reaction, a loss of vibrational memory was observed: here the quantum state distribution of the products is essentially independent of the vibrational excitation of the reactants and results from a sudden decay of the activated complex. More subtle variations of the underlying principle could be identified studying the H+CHD3 → H2 +CD3 reaction: vibrational excitation of the reactant can slightly alter the geometry of the effective dynamical transition state and thereby indirectly affect the product distribution. The resulting picture of quantum state-specific chemistry can be viewed as a natural extension of standard textbook chemistry: the transition state plays the key role and control of the reaction path can be achieved via designed modifications of the transition state. The dependence of a molecule’s reactivity on its initial vibrational quantum state can be explained along the same lines if the principle of microscopic reversibility is utilized and the sudden decay of the activated complex towards reactant is considered. The quantum states of the reactants which are most strongly populated in course of this decay are the ones which show the highest reactivity. While most results can be explained using these simple and intuitive ideas, further complexity can appear as a consequence of system-specific quantum effects, e.g., the reactivity borrowing resulting from Fermi resonance-type state mixing.

Projektbezogene Publikationen (Auswahl)

 
 

Zusatzinformationen

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