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Please acknowledge like this: 
funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – CRC/SFB 1636 – Project ID 510943930 - Project No. A01/B05/Z01


A.R. Ramos, E.W. Fischer,  P. Saalfrank, O. Kühn

Shaping the laser control landscape of a hydrogen transfer reaction by vibrational strong coupling. A direct optimal control approach

J. Chem. Phys. 21 February 2024; 160 (7): 074101. 

Controlling molecular reactivity by shaped laser pulses is a long-standing goal in chemistry. Here, we suggest a direct optimal control approach that combines external pulse optimization with other control parameters arising in the upcoming field of vibro-polaritonic chemistry for enhanced controllability. The direct optimal control approach is characterized by a simultaneous simulation and optimization paradigm, meaning that the equations of motion are discretized and converted into a set of holonomic constraints for a nonlinear optimization problem given by the control functional. Compared with indirect optimal control, this procedure offers great flexibility, such as final time or Hamiltonian parameter optimization. A simultaneous direct optimal control theory will be applied to a model system describing H-atom transfer in a lossy Fabry–Pérot cavity under vibrational strong coupling conditions. Specifically, optimization of the cavity coupling strength and, thus, of the control landscape will be demonstrated.

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E.W. Fischer, J.A. Syska, and P. Saalfrank

A Quantum Chemistry Approach to Linear Vibro-Polaritonic Infrared Spectra with Perturbative Electron–Photon Correlation

The Journal of Physical Chemistry Letters 2024 15 (8), 2262-2269

In the vibrational strong coupling (VSC) regime, molecular vibrations and resonant low-frequency cavity modes form light−matter hybrid states, vibrational polaritons, with characteristic infrared (IR) spectroscopic signatures. Here, we introduce a molecular quantum chemistry-based computational scheme for linear IR spectra of vibrational polaritons in polyatomic molecules, which perturbatively accounts for nonresonant electron−photon interactions under VSC. Speci cally, we formulate a cavity Born− Oppenheimer perturbation theory (CBO-PT) linear response approach, which provides an approximate but systematic description of such electron−photon correlation e ects in VSC scenarios while relying on molecular ab initio quantum chemistry methods. We identify relevant electron−photon correlation e ects at the second order of CBO-PT, which manifest as static polarizability-dependent Hessian corrections and an emerging polar- izability-dependent cavity intensity component providing access to transmission spectra commonly measured in vibro-polaritonic chemistry. Illustratively, we address electron−photon correlation e ects perturbatively in IR spectra of CO2 and Fe(CO)5 vibro-polaritonic models in sound agreement with nonperturbative CBO linear response theory.

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