Ehrenfest and classical path dynamics with decoherence and detailed balance

Area of Science:

• Quantum dynamics
• Molecular modeling
• Computational chemistry

Background:

• Nonadiabatic molecular dynamics are crucial for understanding chemical reactions.
• Existing methods like surface hopping are stochastic and computationally intensive.
• Accurate simulation of quantum effects in nanoscale systems remains challenging.

Purpose of the Study:

• To present a novel semiclassical approach for nonadiabatic molecular dynamics.
• To incorporate decoherence and detailed balance corrections into the Ehrenfest method.
• To provide an efficient and deterministic simulation technique for quantum dynamics.

Main Methods:

• Developed the Ehrenfest-decoherence-detailed-balance (Ehrenfest-DDB) method.
• Introduced a coherence penalty functional for decoherence.
• Modified off-diagonal matrix elements with a quantum correction factor for detailed balance.
• Applied the method to ab initio time-dependent density functional theory and the classical path approximation.

Main Results:

• Ehrenfest-DDB preserves the simplicity of deterministic dynamics with a single trajectory.
• The method shows similar time scales to decoherence-induced surface hopping for nanoscale systems.
• Detailed balance corrections lead to dynamics slowing down at long times, approaching Boltzmann equilibrium.
• The approach is efficient for studying quantum dynamics in large systems.

Conclusions:

• The Ehrenfest-DDB method offers an efficient and deterministic alternative for nonadiabatic molecular dynamics.
• It accurately captures quantum effects like decoherence and detailed balance.
• This technique is suitable for simulating complex nanoscale systems, including those studied with scanning tunneling microscopy.