Vibrational response functions for multidimensional electronic spectroscopy: From Duschinsky rotations to multimode...

Area of Science:

• Quantum dynamics
• Spectroscopy
• Computational chemistry

Background:

• Multidimensional spectroscopy reveals coupled nuclear and electronic dynamics in ultrafast systems.
• Simulations often involve Duschinsky rotations, linear transformations of normal coordinates due to field-induced electronic transitions.

Purpose of the Study:

• To present a novel approach for calculating response functions in molecular dynamics.
• To simplify the numerical derivation of these functions by avoiding complex computational methods.

Main Methods:

• Explicitly deriving the vibrational state, which is shown to be a multimode squeezed coherent state.
• Utilizing a quantum-optical formalism involving rotation, displacement, and squeeze operators.

Main Results:

• The derived vibrational state simplifies response function calculations.
• The approach avoids time integration of the Schrödinger equation, Hamiltonian diagonalization, and summing over infinite vibronic pathways.
• It provides quantitative support for interpreting response functions via vibrational wave packet dynamics.

Conclusions:

• The proposed quantum-optical method offers a computationally efficient alternative for studying ultrafast molecular dynamics.
• This approach enhances the intuitive understanding of response functions in terms of vibrational wave packet motion.