Nonadiabatic dynamics simulation of photoinduced ring-opening reaction of 2(5H)-thiophenone with internal conversion and intersystem crossing

Abstract

In the present work, the quantum trajectory mean-field approach, which is able to overcome the overcoherence problem, was generalized to simulate internal conversion and intersystem crossing processes simultaneously. The photoinduced...

Monitoring the Evolution of Relative Product Populations at Early Times during a Photochemical Reaction

“…Among these ketenes, an exotic episulfide species, 2-(2-thiiranyl)-ketene, involving an S-containing three-membered ring, has been predicted to dominate at early times following the nonradiative deexcitation (Scheme 1). 22,25,26 The formation of a three-membered ring from a fivemembered cyclic species following the absorption of a 266 nm photon, with 4.65 eV of energy, might appear to challenge chemical intuition. Our recent TRPES studies using suitably short probe wavelengths 22 succeeded in resolving the ultrafast nonradiative decay of 2(5H)-thiophenone from its second excited singlet electronic state (S 2 , with n(S)π* character in the Franck−Condon region) following photoexcitation at 266 nm (Figure 1A) and in revealing the formation of acyclic photoproducts.…”

Ab initio molecular dynamics study of intersystem crossing dynamics for MH2 (M = Si, Ge, Sn, Pb) on spin‐pure and spin‐mixed potential energy surfaces

“…In studying ISC by SH‐AIMD simulations, there are two choices of potential energy surface (PES): one in the spin‐pure state and the other in the spin‐mixed state. For systems with small SOC, the difference between the two PESs is not so large that it is efficient to use the spin‐pure state PESs from a computational cost viewpoint, and SOC is only considered when evaluating transition probabilities 19–21,33–36 . However, for systems with large SOC, it is necessary to use the spin‐mixed PESs even in the time evolution of the nuclei; SOC affects the nuclear motion via the potential energy gradient and the NAC term.…”

“…Recently, there has been a gradual increase in the number of studies performing SH-AIMD calculations for the intersystem crossing problems using either of TFS or ZN method. [19][20][21]27,[31][32][33][34][35][36] In this study, to discuss the applicability of the SH-AIMD method to excited-state reactions with intersystem crossings in molecular systems, we perform spin-pure and spin-mixed PES-based SH-AIMD simulations for group 14 element dihydrides MH 2 (M = Si, Ge, Sn, Pb) with different SOC strength. Spin-pure and spin-mixed PESs for these systems have been investigated by a previous study.…”

Generalized Ab Initio Nonadiabatic Dynamics Simulation Methods from Molecular to Extended Systems

“…Unfortunately, it will face an insurmountable computational problem and be limited to very small systems. Alternatively, the mixed quantum-classical (MQC) nonadiabatic dynamics simulations have been proposed to investigate the photoinduced excited-state relaxation processes for polyatomic systems in the past decades, of which nuclei are treated classically while electrons are done quantum mechanically. − Trajectory-based surface hopping (TSH) becomes one of the most prominent MQC nonadiabatic dynamics methods due to its simple framework and feasible computational cost. , It is the basis for some well-known dynamics programs, such as Newton-X, SHARC, PYXIAD, GTSH, etc. − However, the original TSH method proposed by Tully et al has several limitations, e.g., lacking of quantum decoherence and incapable of simulating intersystem crossing. , To overcome these problems, several strategies have been put forward to account for quantum decoherences − and intersystem crossing processes. ,,− …”

“…In recent years, our group is devoted to developing the MQC dynamics methods and attempts to overcome the limitations that exist in nonadiabatic dynamics simulations. − Among them, the TSH-based GTSH method has been designed to treat internal conversion and intersystem crossing simultaneously, since the spin–orbit effects usually play an important role in photochemistry, not just on the heavy-atom systems. In this Feature Article, we will present our recently developed GTSH method, its numerical implementation at the ab initio level, and also some of the latest applications in realistic photochemical systems.…”