A generalized vibronic-coupling Hamiltonian for molecules without symmetry: Application to the photoisomerization of benzopyran

Benjamin Gonon; Benjamin Lasorne; Gabriel Karras; Loïc Joubert-Doriol; David Lauvergnat; Franck Billard; Bruno Lavorel; Olivier Faucher; Stephane Guerin; Edouard Hertz; Fabien Gatti

A generalized vibronic-coupling Hamiltonian for molecules without symmetry: Application to the photoisomerization of benzopyran

Benjamin Gonon ¹ Benjamin Lasorne ¹ Gabriel Karras ² Loïc Joubert-Doriol ^{1, 3} David Lauvergnat ⁴ Franck Billard ² Bruno Lavorel ² Olivier Faucher ² Stephane Guerin ² Edouard Hertz ² Fabien Gatti ^{1, 5}

1 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

2 LICB - Laboratoire Interdisciplinaire Carnot de Bourgogne [Dijon]

3 MSME - Laboratoire de Modélisation et Simulation Multi Echelle

4 LCPO - Laboratoire de Chimie Physique D'Orsay

5 ISMO - Institut des Sciences Moléculaires d'Orsay

Abstract : We present a model for the lowest two potential energy surfaces (PESs) that describe the photoinduced ring-opening reaction of benzopyran taken as a model compound to study the photochromic ring-opening reaction of indolinobenzospiropyran and its evolution toward its open-chain analog. The PESs are expressed in terms of three effective rectilinear coordinates. One corresponds to the direction between the equilibrium geometry in the electronic ground state, referred to as the Franck-Condon geometry, and the minimum of conical intersection (CI), while the other two span the two-dimensional branching space at the CI. The model correctly reproduces the topography of the PESs. The ab initio calculations are performed with the extended multiconfiguration quasidegenerate perturbation theory at second order method. We demonstrate that accounting for electron dynamic correlation drastically changes the global energy landscape since some zwitterionic states become strongly stabilized. Quantum dynamics calculations using this PES model produce an absorption spectrum that matches the experimental one to a good accuracy.

Keywords : Potential energy surfaces Quantum mechanical principles Quantum chemical dynamics Photochemical reactions Photochromism Absorption spectroscopy Organic compounds Perturbation theory

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Chimie

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https://hal.umontpellier.fr/hal-02108321
Contributeur : Odile Hennaut <>
Soumis le : samedi 18 mai 2019 - 10:41:47
Dernière modification le : mercredi 4 septembre 2019 - 13:52:14

A generalized vibronic-coupling Hamiltonian for molecules without symmetry: Application to the photoisomerization of benzopyran

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A generalized vibronic-coupling Hamiltonian for molecules without symmetry: Application to the photoisomerization of benzopyran

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