COSMOS Quantum Nonadiabatic Dynamics Afternoon - 2024
On Friday 22nd March, Dmitry Shalashilin and his local team at the University of Leeds hosted an afternoon event featuring talks from Sergei Tretiak and Anastasia Bochenkova. As the first opportunity for the COSMOS Senior Team to meet in person it was a great opportunity for introductions and collaboration alongside two fantastic scientific contributions.
Probing dynamics of chemical bonds in organic chromophores by X-ray spectroscopies
Sergei Tretiak
Theoretical Division, Center for Nonlinear Studies and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos NM, 87545
Chemical bonding patterns fundamentally change when molecules dynamically evolve in electronically excited states created by optical excitations. These dynamics give rise to many useful properties and functionalities, which can be resolved in space and time at modern XFEL facilities. In this talk I will overview some possible measurements that can be done with X-ray lasers suggested by computational investigations using excited state non-adiabatic dynamics approaches. In the first example, we use dynamical simulations to compute X-ray Raman signals, which are able to monitor the coherence evolution in molecular photoswitches. Time-resolved X-ray diffraction can further probe key chemical features during the ultrafast dynamics. In the first example, X-ray Circular Dichroism (XCD) can exploit the localized and element-specific nature of X-ray electronic transitions. XCD therefore is more sensitive to local structures and the chirality probed with it can be referred to as local which in contrast to a conventional Optical Circular Dichroism probing the global molecular chirality.
Relevant references
V. M. Freixas, W. Malone, X. Li, H. Song, H. Negrin-Yuvero, A. White, T. R. Gibson, D. V. Makhov, D. V. Shalashilin, Y. Zhang, N. Fedik, M. Kulichenko, R. Messerly, L. N. Mohanam, S. Sharifzadeh, A. Bastida, S. Fernandez-Alberti, and S. Tretiak “NEXMD2 Software Package for Nonadiabatic Excited State Molecular Dynamics Simulations,” J. Chem. Theory Comput., 19, 5356 – 5368 (2023).
Y. Nam, H. Song, V. M. Freixas, S. Fernandez-Alberti, D. Keefer, Jin Yong, M. Garavelli, S. Tretiak, and S. Mukamel “Monitoring vibronic coherences and molecular aromaticity in photoexcited cyclooctatetraene with an X-ray probe: a simulation study,” Chem. Sci., 14, 2971 (2023).
V. M. Freixas, J. R. Rouxel, Y. Nam, S. Tretiak, N. Govind, S. Mukamel, “X‐ray and Optical Circular Dichroism as Local and Global Ultrafast Chiral Probes of [12]Helicene Racemization”, J. Am. Chem. Soc., 145, 21012 (2023)
Theoretical and Computational Photochemistry of Light-Sensitive Biosystems
Anastasia V. Bochenkova
Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
We will discuss a general theoretical framework of the XMCQDPT2 method, which is based on quasi-degenerate perturbation theory for effective Hamiltonians, and its applications to the studies of the photochemistry of the retinal protonated Schiff base and its derivatives. By using XMCQDPT2, we have provided for the first time a highly accurate reference for excited-state lifetimes of various isomers of isolated RPSBs and have shown that the protein environment can change both the timescale and the specificity of the RPSB isomerization. We have also discovered a way how to significantly accelerate and steer the nonadiabatic dynamics of native RPSB. By using molecular dynamics simulations and large-scale XMCQDPT2-based QM/MM modeling, we have explored the origin of reactive and nonreactive states in retinal-containing proteins. By calculating vibronic band shapes, we have gained insight into the early-time excited-state dynamics of RPSB inside visual and microbial rhodopsins and have shown that the protein environment can significantly alter vibrational modes that become active upon photoexcitation, thus facilitating the specific photoisomerization. The obtained results provide direct evidence of accurate excited-state potentials that one might be able to calculate through the XMCQDPT2 formalism. The XMCQDPT2 method has also been extended to study electron photodetachment in the gas phase and solution.
References
Bochenkova, A.V. Multiconfigurational Methods Including XMCQDPT2 Theory for Excited States of Light-Sensitive Biosystems. In: Yanez, Manuel and Boyd, Russell J. (eds.) Comprehensive Computational Chemistry, Vol. 4, pp. 141–157. Oxford: Elsevier. (2024)
Kiefer, H.V., Gruber, E., Langeland, J., et al. Intrinsic photoisomerization dynamics of protonated Schiff-base retinal. Nat. Commun. 10, 1210 (2019).
Gruber, E., Kabylda, A.M., Nielsen, M.B., et al. Light driven ultrafast bioinspired molecular motors: Steering and accelerating photoisomerization dynamics of retinal. J. Am. Chem. Soc. 144, 69–73 (2022).
Kusochek, P.A., Scherbinin, A.V., Bochenkova, A.V. Insights into the early-time excited-state dynamics of structurally inhomogeneous rhodopsin KR2. J. Phys. Chem. Lett. 12, 8664–8671 (2021)
Bochenkova, A.V., Mooney Ciaran, R.S., Parkes, M.A., et al. Mechanism of resonant electron emission from the deprotonated GFP chromophore and its biomimetics. Chem. Sci. 8, 3154–3163 (2017).
Tau, O., Henley, A., Boichenko, A.N., et al. Liquid-microjet photoelectron spectroscopy of the Green Fluorescent Protein chromophore. Nat. Commun. 13, 507 (2022)
