Vibrational response functions for multidimensional electronic spectroscopy in the adiabatic regime: A coherent-state approach

Multi-dimensional spectroscopy represents a particularly insightful tool for investigating the interplay of nuclear and electronic dynamics, which plays an important role in a number of photophysical processes and photochemical reactions. Here, we present a coherent state representation of the vibronic dynamics and of the resulting response functions for the widely used linearly displaced harmonic oscillator model. Analytical expressions are derived for M-th order response functions of an N-level system, with coherent- and thermal-state initialization of the oscillator(s). The formal derivation is translated into a simple recipe, whereby the explicit analytical expressions of the response functions can be derived directly from the Feynman diagrams. Finally, the application of a non-Hermitian Hamiltonian approach is discussed, which allows us to extend the above results to the case of vibrational relaxation.

References: F. E. Quintela Rodriguez and F. Troiani, J. Chem. Phys. 157, 034107 (2022),

also available at arXiv:2204.01415.