Ultrafast Photoinduced Dynamics of 1,3-Cyclohexadiene Using XMS-CASPT2 Surface Hopping

Abstract

A full-dimensional simulation of the photo-dissociation of 1,3-cyclohexadiene in the manifold of three electronic states was performed via non-adiabatic surface hopping dynamics using extended multi-state complete active space second-order perturbation (XMS-CASPT2) electronic structure theory with fully analytic non-adiabatic couplings. With the 47 ± 8% product quantum yield calculated from the 136 trajectories, generally 400 fs-long, and an estimated excited lifetime of 89±9 fs, our calculations provide a detailed description of the non-adiabatic deactivation mechanism, showing the existence of an extended conical intersection seam along the reaction coordinate. The nature of the preferred reaction pathways on the ground state is discussed and extensive comparison to the previously published full dimensional dynamics calculations is provided.

Molecular Photochemistry: Recent Developments in Theory

“…[172][173][174] Hence, the last decade has seen ah uge effort in developing more accurate and more versatile trajectory-based non-adiabatic dynamics methods,asdocumented in recent reviews. [141,[175][176][177][178][179][180] Thepopularity of TSH because of its simplicity and computational efficiency is recognized in the large number of applications,r anging from chemistry [181][182][183][184][185] to biology, [186][187][188][189][190] from surface chemistry [191][192][193] to conjugated polyene materials, [194] and from molecular rotors [116,195] to transition-metal complexes. [11,196] Tr ajectory-based non-adiabatic dynamics has profited from the recent development of exact factorization theory, [197] which is an alternative to the classical Born-Oppenheimer formalism for treating coupled nuclear-electron dynamics.…”

Mechanism of Photoinduced Dihydroazulene Ring-Opening Reaction

“…However, the lack of analytical nuclear gradients in the available TSH codes and expensive computational cost hamper us to perform the dynamics at this level, although we note that there are a few recent nonadiabatic TSH dynamics studies that have applied MS-CASPT2 using a local implementation of analytic energy gradients. [27][28][29] Therefore, we make use of the (TD)DFT method as a practical alternative to CASSCF. It is well-known that the TDDFT method fails in the vicinity of the S 1 /S 0 CI due to the single-reference character of the ground-state wavefunction.…”

Molekulare Photochemie: Moderne Entwicklungen in der theoretischen Chemie

“…[172][173][174] Ausd iesem Grund wurde im letzten Jahrzehnt ein großer Entwicklungsaufwand hin zu genaueren und flexibleren Tr ajektorien-basierten Verfahren fürn ichtadiabatische Dynamik betrieben, wie in mehreren aktuellen Übersichtsartikeln dargelegt ist. [141,[175][176][177][178][179][180] Die große Popularitätd es TSH-Verfahrens aufgrund seiner Einfachheit und rechnerischen Effizienz lässt sich aus der großen Zahl seiner Anwendungen ablesen, welche von der Chemie [181][182][183][184][185] zur Biologie, [186][187][188][189][190] von Überflächenchemie [191][192][193] bis zu konjugierten Polyenen [194] und von molekularen Rotationsmotoren [116,195] bis zu Übergangsmetallkomplexen [11,196] reichen.…”