title: Ultrafast hydrogen migration in acetylene cation driven by non-adiabatic effects.
abstract: 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.
authors.affiliation: Center for Free-Electron Laser Science, DESY, Notkestrasse 85, D-22607 Hamburg, Germany. mohamed.el.amine.madjet@cfel.de
authors.forename: Mohamed El-Amine
authors.initials: Mel-A
authors.lastname: Madjet
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.forename: Oriol
authors.initials: O
authors.lastname: Vendrell
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties
chemical_list: D002412:Cations; D006859:Hydrogen; D000114:Acetylene