A Vibronic Coupling Model to Study the Nonadiabatic Dynamics of Polyenes

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Quantum dynamics

Background:

• Polyenes exhibit complex electronic dynamics.
• Accurate simulation of these dynamics is crucial for understanding photochemical processes.
• Quantum-classical methods offer a computationally tractable approach.

Purpose of the Study:

• To develop and benchmark a linear vibronic coupling (LVC) model for polyenes.
• To compare the accuracy of surface-hopping and multitrajectory Ehrenfest methods.
• To investigate the long-time dynamics of polyenes using quantum-classical simulations.

Main Methods:

• Development of a linear vibronic coupling (LVC) model based on the extended Hubbard-Peierls Hamiltonian.
• Application of the LVC model to trans-hexatriene.
• Benchmarking quantum-classical dynamics methods against fully quantum simulations.
• Analysis of short-time and long-time population dynamics.

Main Results:

• Surface-hopping methods show higher accuracy for short-time dynamics compared to multitrajectory Ehrenfest.
• Neither quantum-classical method fully reproduces the long-time population oscillations observed in fully quantum simulations.
• Surface hopping captures long-time dynamics trends across various parameters but overestimates internal conversion.
• Multitrajectory Ehrenfest provides more accurate long-time populations near the hexatriene parameter set.

Conclusions:

• The developed LVC model provides a valuable tool for studying polyene dynamics.
• Quantum-classical methods have limitations in accurately describing long-time dynamics, particularly population oscillations.
• Surface-hopping and multitrajectory Ehrenfest exhibit distinct strengths and weaknesses depending on the timescale and system parameters.