Mixed quantal-semiquantal dynamics with stochastic particles for backreaction

Area of Science:

• Chemical Physics
• Quantum Mechanics
• Surface Science

Background:

• Accurate simulation of heavy particle dynamics in quantum systems is computationally challenging.
• Mean-field approximations often neglect crucial interparticle correlations and quantum backreaction effects.

Purpose of the Study:

• To develop an improved theoretical framework for simulating quantum-classical systems.
• To incorporate interparticle correlations and quantum backreaction beyond the mean-field approximation.

Main Methods:

• A mixed quantal-semiquantal theory is presented, employing semiquantal squeezed-state wave packets for heavy degrees of freedom.
• A stochastic particle description is introduced for both quantal and semiquantal components to capture correlations.
• The theory is applied to a model of O2 scattering from a Pt surface.

Main Results:

• The proposed scheme accurately reproduces the asymptotic behavior of scattering probabilities.
• The stochastic particle approach demonstrates improved accuracy compared to mixed quantum-classical methods using Bohmian particles.
• Analysis of stochastic and Bohmian trajectories reveals the advantages of the new method.

Conclusions:

• The developed mixed quantal-semiquantal theory with stochastic particles offers a more accurate description of quantum-classical dynamics.
• This approach effectively accounts for quantum backreaction, leading to better predictions in scattering problems.
• The findings suggest a promising direction for simulating complex chemical and physical processes at surfaces.