We have simulated femtosecond two-dimensional (2D) electronic spectra for an excited-state conical intersection using the wave-function version of the equation-of-motion phase-matching approach. We show that 2D spectra at fixed values of the waiting time provide information on the structure of the vibronic eigenstates of the conical intersection, while the evolution of the spectra with the waiting time reveals predominantly ground-state wave-packet dynamics. The results show that 2D spectra of conical intersection systems differ significantly from those obtained for chromophores with well separated excited-state potential-energy surfaces. The spectral signatures which can be attributed to conical intersections are discussed.
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http://dx.doi.org/10.1063/1.4928685 | DOI Listing |
Nat Phys
November 2024
Laboratory of Physical Chemistry, ETH Zürich, Zurich, Switzerland.
A dynamical rearrangement in the electronic structure of a molecule can be driven by different phenomena, including nuclear motion, electronic coherence or electron correlation. Recording such electronic dynamics and identifying its fate in an aqueous solution has remained a challenge. Here, we reveal the electronic dynamics induced by electronic relaxation through conical intersections in both isolated and solvated pyrazine molecules using X-ray spectroscopy.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
The quantum transition state framework was developed to calculate the reaction path-resolved scattering matrix for atom-diatom reactions in hyperspherical (APH) coordinates. This approach allows for simply and directly calculating the reaction path-resolved scattering matrix, especially when the encircling reaction path is negligible. It could be used to determine the reactivities of specific pathways in a chemical reaction, providing insights into phenomena such as geometric phase effects.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.
The ground and excited state electronic structure of the molecular photoswitches quadricyclane and norbornadiene is examined qualitatively and quantitatively. A new custom basis set is introduced, optimised for efficient yet accurate calculations. A number of advanced multi-configurational and multi-reference electronic structure methods are evaluated, identifying those sufficiently accurate and efficient to be used in on-the-fly simulations of photoexcited dynamics.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
In this study, the radiative and nonradiative decay pathways from the first singlet excited states (denoted as S) of three bithiophene-fused isoquinolines were investigated by using the mixed-reference spin-flip time-dependent density functional theory approach. These isoquinolines, which are prepared via [2 + 2 + 2] cycloaddition reactions between three types of bithiophene-linked diynes and nitriles, exhibit different fluorescence quantum yields in response to the positions of their sulfur atoms. The decay processes, including the fluorescence emission and internal conversion, were considered.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Department of Chemistry, Norwegian University of Science and Technology, NTNU, 7491 Trondheim, Norway.
Coupled cluster theory in the standard formulation is unable to correctly describe conical intersections among states of the same symmetry. This limitation has restricted the practical application of an otherwise highly accurate electronic structure model, particularly in nonadiabatic dynamics. Recently, the intersection problem among the excited states was fully characterized and resolved.
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