Generalization of Quantum-Trajectory Surface Hopping to Multiple Quantum States.

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Theoretical Chemistry

Background:

• Nonadiabatic dynamics simulations are crucial for understanding chemical reactions.
• Existing surface hopping methods often face limitations in energy conservation and accuracy.
• The quantum trajectory surface hopping (QTSH) method offers an alternative approach.

Purpose of the Study:

• To generalize the quantum trajectory surface hopping (QTSH) method to multiple states.
• To implement the multistate QTSH in the Libra package for nonadiabatic dynamics.
• To compare the performance of QTSH with decoherence corrections against conventional methods.

Main Methods:

• Developed a multistate quantum trajectory surface hopping (QTSH) approach.
• Implemented QTSH using quantum forces for continuous nuclear evolution.
• Integrated decoherence corrections: simplified decay of mixing (SDM) and exact factorization (XF).
• Applied QTSH-SDM and QTSH-XF to Holstein, superexchange, and phenol model systems.

Main Results:

• The generalized QTSH method conserves total energy at the ensemble level, not the individual trajectory level.
• QTSH utilizes quantum forces, avoiding ad hoc velocity rescaling.
• Combined QTSH with decoherence corrections (QTSH-SDM, QTSH-XF) significantly improves accuracy.
• Decoherence corrections are vital for energy conservation and population consistency in QTSH.

Conclusions:

• The multistate QTSH with decoherence corrections provides a more accurate and consistent approach for nonadiabatic dynamics.
• This method overcomes limitations of traditional surface hopping techniques.
• The developed QTSH implementation in Libra enhances capabilities for simulating complex chemical processes.