Ultrafast hydrogen migration in acetylene cation driven by non-adiabatic effects.

Non-adiabatic dynamics of the acetylene cation is investigated using mixed quantum-classical dynamics based on trajectory surface hopping. To describe the non-adiabatic effects, two surface hopping methods are used, namely, Tully's fewest switches and Landau-Zener surface hopping. Similarities and differences between the results based on those two methods are discussed. We find that the photoionization of acetylene into the first excited state A(2)Σg(+) drives the molecule from the linear structure to a trans-bent structure. Through a conical intersection the acetylene cation can relax back to either the ground state of acetylene or vinylidene. We conclude that hydrogen migration always takes place after non-radiative electronic relaxation to the ground state of the monocation. Based on the analysis of correlation functions we identify coherent oscillations between acetylene and vinylidene with a period of about 70 fs after the electronic relaxation.

Citation

Mohamed El-Amine Madjet, Zheng Li, Oriol Vendrell. Ultrafast hydrogen migration in acetylene cation driven by non-adiabatic effects. The Journal of chemical physics. 2013 Mar 7;138(9):094311

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PMID: 23485298

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