Semiclassical Investigation of Nuclear Quantum Effects in Chemical Kinetics and Vibrational Spectroscopy

Aug 5, 2026

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Nuclear Quantum Effects (NQE) shape chemical behavior in both reaction kinetics and vibrational spectroscopy. Incorporating Zero Point Energy (ZPE) and tunneling provides explanations for anomalous reaction-rate constants, while in spectroscopy spectral splittings and shifts can arise from tunneling and quantum delocalization/localization. The talk outlines semiclassical approaches that are rigorous yet feasible for atomistic simulations to predict quantum-mechanical signatures. It focuses on SCTST for tunneling and ZPE beyond classical TST and SC-IVR-MD for accurate vibrational spectra and quantum eigenfunctions, correcting limitations of purely classical MD sampling.

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Abstract

Nuclear Quantum Effects in kinetics

Nuclear Quantum Effects in spectroscopy

Semiclassical methods: SCTST

Semiclassical methods: SC-IVR-MD

Implications for atomistic simulations

Semiclassical investigation of nuclear quantum effects in chemical kinetics and vibrational spectroscopy Chiara Donatella Aieta Università degli Studi di Milano Abstract Nuclear Quantum Effects (NQE) manifest in chemistry in both kinetics and spectroscopy fields. Accounting for the Zero Point Energy (ZPE) and tunneling phenomena can explain unexpected experimental observations of reaction rate constants.[1,2] Also, in spectroscopy, some spectral features, such as signal splittings or shifts, are due to tunneling phenomena or quantum delocalization (or localization), which cause the system to sample the potential energy surface in anon-classical way.[3,4] Rigorous but at the same time, affordable methods to include NQE in atomistic simulations must be developed to predict and explain experimental quantum mechanical hallmarks. This talk will describe semiclassical approaches for kinetics and spectroscopic applications. Specifically, the Semiclassical Transition State Theory (SCTST) can include tunneling and ZPE effects at a higher level of theory than widespread tunneling corrections for classical TST rate calculations.[5-7] Then, the Semiclassical Initial Value Representation Molecular Dynamics (SC-IVR-MD) can predict accurate vibrational spectra and even reproduce vibrational quantum eigenfunctions.[9,10] Thus, the SC-IVR-MD technique can reproduce the quantum mechanical sampling of the potential energy surface, fixing purely classical MD vibrational spectroscopy pitfalls.[11] References [1]J. Meisner, J. Kästner, Angew. Chem. Int. Ed., 55, 5400-5413 (2016) [2]P. Schreiner, Trends in Chemistry, 2, 980-989 (2020) [3]F. Gabas, G. Di Liberto, R. Conte, M. Ceotto, Chem. Sci., 9, 7894-7901 (2018) [4]R. Conte, A. Aspuru-Guzik, M. Ceotto, J. Phys. Chem. Lett., 4, 3407-3412 (2013) [5]W. Miller, R. Hernandez, N. Handy, D. Jayatilaka, A. Willetts, Chemical Physics Letters, 172, 62-68 (1990) [6]C. Aieta, F. Gabas, M. Ceotto, J. Phys. Chem. A, 120, 4853-4862 (2016) [7]C. Aieta, F. Gabas, M. Ceotto, J. Chem. Theory Comput., 15, 2142-2153 (2019) [8]G. Mandelli, C. Aieta, M. Ceotto, J. Chem. Theory Comput., 18, 623-637 (2022) [9]C. Aieta, M. Micciarelli, G. Bertaina, M. Ceotto, Nat. Commun., 11, 4348 (2020) [10]C. Aieta, G. Bertaina, M. Micciarelli, M. Ceotto, The Journal of Chemical Physics, 153,(2020) [11]R. Conte, C. Aieta, G. Botti, M. Cazzaniga, M. Gandolfi, C. Lanzi, G. Mandelli, D. Moscato, M. Ceotto, Theor. Chem. Acc., 142, 53 (2023)

FAQs

How do Nuclear Quantum Effects influence chemical kinetics and reaction rates?

NQE, through Zero Point Energy (ZPE) and tunneling, can account for unexpected experimental reaction-rate constants when incorporated into modeling.

What causes spectral splittings or shifts in vibrational spectroscopy according to the talk?

The talk attributes these features to tunneling phenomena and quantum delocalization (or localization), which change how the system samples the potential energy surface.

What is the role of SCTST and SC-IVR-MD in including NQE?

Semiclassical Transition State Theory (SCTST) includes tunneling and ZPE effects at a higher level than common tunneling corrections for classical TST. Semiclassical Initial Value Representation Molecular Dynamics (SC-IVR-MD) predicts accurate vibrational spectra and can reproduce vibrational quantum eigenfunctions.

Aug 5, 2026

Upload by Quinn