Two-dimensional vibronic spectroscopy with semiclassical thermofield dynamics.

Area of Science:

• Quantum mechanics
• Spectroscopy
• Computational chemistry

Background:

• Thermofield dynamics offers a quantum mechanical framework for finite-temperature systems.
• The optimized mean trajectory (OMT) approximation uses classical trajectories from a mapping Hamiltonian to compute spectroscopic responses.
• Existing methods require accurate quantum treatments at finite temperatures.

Purpose of the Study:

• To develop a thermofield optimized mean trajectory (TF-OMT) approach.
• To apply TF-OMT to calculate spectroscopic response functions for systems with excitonically coupled electronic states.
• To validate TF-OMT by comparing its results with established methods.

Main Methods:

• Developed a TF-OMT approach by applying the OMT procedure to a temperature-dependent classical Hamiltonian derived from the thermofield-transformed quantum mapping Hamiltonian.
• Sampled initial conditions for bath nuclear degrees of freedom from a zero-temperature distribution.
• Calculated two-dimensional electronic and vibrational-electronic spectra for models with coupled electronic states.

Main Results:

• TF-OMT calculations showed excellent agreement with standard OMT results.
• The results were also consistent with benchmark calculations using the hierarchical equations of motion method.
• Demonstrated the applicability of TF-OMT for simulating spectroscopic properties at finite temperatures.

Conclusions:

• The developed TF-OMT method provides an accurate and efficient approach for quantum mechanical simulations at finite temperatures.
• TF-OMT successfully captures spectroscopic properties of systems with excitonically coupled electronic states.
• This method offers a valuable tool for theoretical spectroscopy and computational chemistry.