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Hannover 2016 – scientific programme

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MO: Fachverband Molekülphysik

MO 20: Femtosecond Spectroscopy 4

MO 20.5: Talk

Friday, March 4, 2016, 12:00–12:15, f102

Quantum dynamics of molecular reactions in an explicit solvent cage — •Sebastian Thallmair1,2, Julius Zauleck1, and Regina de Vivie-Riedle11Department Chemie, LMU München — 2LS für BioMolekulare Optik, LMU München

Solvents are a crucial factor in every day chemistry. Additionally to electrostatic effects, dynamic solvent effects can emerge during ultrafast reactions with large amplitude molecular motion. We showed their importance for the photochemical bond cleavage of diphenylmethylphosphonium ions in solution [1] which is a common way to generate highly reactive carbocations.

Recently, we developed a new method combining quantum dynamics (QD) and classical molecular dynamics (MD) to model the influence of an explicit solvent environment on the QD of molecular reactions [2]. In this QD/MD approach, we extract the solvent potential from the MD trajectories by evaluating a set of different snapshots. Each solvent arrangement is taken into account individually and its potential is included in the Hamiltonian used for the QD calculations. The solute Hamiltonian is set up in specially designed reactive coordinates and the potential energy surfaces are evaluated at the ONIOM/ CASSCF(10,10)/M06-2X level of theory. The solvent cage hinders the free dissociation and guides the molecular wave packet to the conical intersection which is not accessible in the gas phase. There the experimentally observed diphenylmethyl cations are formed.

[1] S. Thallmair et al., J. Chem. Phys. Lett. 5, 3480 (2014).

[2] S. Thallmair et al., J. Chem. Theory Comput. 11, 1987 (2015).

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