Berlin 2014 – scientific programme

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MO: Fachverband Molekülphysik

MO 19: Femtosecond Spectroscopy 2

MO 19.2: Talk

Thursday, March 20, 2014, 16:45–17:00, BEBEL HS213

Quantum dynamical studies of diphenylmethylchloride including geometry relaxation and a three-state conical intersection seam — •Matthias K. Roos, Sebastian Thallmair, and Regina de Vivie-Riedle — Department Chemie, Ludwig-Maximilians-Universität München

Reactive species like carbocations and -radicals are ubiquitous in organic synthesis. A convenient precursor for such intermediates is diphenylmethylchloride that is undergoing a carbon-chlorine bond cleavage after laser irradition. We are using quantum chemical and quantum dynamical methods to evaluate the branching ratio between product pathways through consecutive conical intersections for this sub-picosecond ultrafast dissociation reaction. We present a new reduced coordinate space to describe the reaction using the Wilson G matrix approach for the kinetic Hamiltonian. With this method we can use combined internal coordinates that particularly account for all relaxation in the molecule during the dissociation process.

Resulting 1D and 2D potential energy surfaces on the ONIOM(CASSCF(12,10)/B3LYP) level of theory are presented and compared with respect to the approximation applied. Especially the influence of the chlorine lone pairs is discussed that have a significant impact on the dissociation dynamics through a prominent three-state conical intersection seam in the Franck-Condon region. The shape of the G matrix elements can be traced back to the relaxation included in the chosen coordinates. Dynamical results taking into account all relevant conical intersections are presented.