Decoherence-induced adaptive multiconfigurational Ehrenfest dynamics for nonadiabatic scattering simulations.

Area of Science:

• Quantum dynamics
• Theoretical chemistry
• Computational physics

Background:

• Simulating nonadiabatic scattering dynamics requires careful handling of electronic coherence and decoherence.
• Traditional Ehrenfest methods face an 'overcoherence' problem due to electronic state entanglement with nuclear motion.

Purpose of the Study:

• To develop a method that simultaneously treats coherent propagation and quantum decoherence in nonadiabatic scattering.
• To address the limitations of existing theoretical simulations in capturing complex quantum dynamics.

Main Methods:

• Investigated multiconfigurational Ehrenfest (MCE) dynamics with adaptive basis set expansion.
• Proposed a decoherence-induced adaptive MCE (DA-MCE) method inspired by mixed quantum-classical dynamics.
• Applied the DA-MCE method to the three famous Tully models.

Main Results:

• DA-MCE efficiently captures the time evolution of the reduced density matrix and Stueckelberg interference.
• The method successfully models rapid decoherence in nonadiabatic scattering dynamics.
• Adaptive basis set expansion and the variational Ansatz form are crucial for describing complex dynamics.

Conclusions:

• DA-MCE provides a robust framework for simulating nonadiabatic scattering dynamics with both coherence and decoherence.
• The method offers a multiconfigurational alternative to branching corrected mean field methods.
• DA-MCE shows potential for integration with general mixed quantum-classical trajectory approaches.