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Computational modeling of non-adiabatic chemistry at the conical intersection seam in polyatomic molecules

David Mendive-Tapia, CEISAM (Nantes)

Séminaire LCPQ

Salle 20 RdC

Mercredi 3 Décembre 2014, 14h30-15h30

Non-adiabatic chemistry is a term employed to describe reactions in which two or more coupled potential energy surfaces are involved. Their theoretical modeling is a challenging topic since the description must treat simultaneously the motion of the nuclei and the electrons, which are coupled together and significantly impacted by quantum-mechanical effects. In this review talk we shall give a brief overview of some of our recent work in this field through three representative examples :

• First, we will address the interpretation of mechanistic principles through a stationary picture of the relevant potential energy surfaces using as example the recently proposed fatigue mechanism in diarylethenes.[1]

• Second, the simulation of electron dynamics via an Ehrenfest-based CASSCF dynamics methodology applied to 2-phenylethylamine and substituted benzenes.[2]

• Third, the simulation of nuclear dynamics via “on-the-fly†Heller’s type variational Gaussian wavepackets using as example fulvene ultrafast radiationless decay.[3]

Last, we will present the future perspective on the use and development of a Multi Layer scheme within the MCTDH formalism,[4] which could open the door for grid-based nuclear quantum dynamics simulations in medium/large size systems (more than 10 atoms) comparable to the introduction of contracted Gaussian basis sets in electronic structure theory.

[1] D. Mendive-Tapia, A. Perrier, M. J. Bearpark, M. A. Robb, B. Lasorne, D. Jacquemin, "New insights into the by-product fatigue mechanism of the photo-induced ring-opening in diarylethenes", Physical Chemistry Chemical Physics, vol. 16, 2014.

[2] D. Mendive-Tapia, M. Vacher, M. J. Bearpark, M. A. Robb, "Coupled electron-nuclear dynamics : charge migration and charge transfer initiated near a conical intersection", Journal of Chemical Physics, vol. 139, 2013.

[3] D. Mendive-Tapia, B. Lasorne, G. A. Worth, M. J. Bearpark, and M. A. Robb, "Controlling the mechanism of fulvene S-1/S-0 decay : switching off the stepwise population transfer," Physical Chemistry Chemical Physics, vol. 12, pp. 15725-15733, 2010.

[4] Manthe, U. “A multilayer multiconfigurational time-dependent Hartree approach for quantum dynamics on general potential energy surfaces†, Journal of Chemical Physics, 128, 164116, 2008.