Quantum wave packet ab initio molecular dynamics: an approach to study quantum dynamics in large systems

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Molecular Modeling

Background:

• Simulating the coupled motion of electrons and nuclei is crucial for understanding chemical reactions.
• Existing methods often struggle to efficiently and accurately treat both quantum and classical aspects simultaneously.

Purpose of the Study:

• To develop an efficient computational methodology for simultaneous quantum wave packet dynamics of electrons and nuclei.
• To accurately incorporate quantum mechanical effects in molecular dynamics simulations.

Main Methods:

• Combines quantum wave packet dynamics with ab initio molecular dynamics (AIMD).
• Employs a banded, sparse, and Toeplitz representation for the discrete free propagator.
• Utilizes a time-dependent self-consistent field-like coupling procedure.
• Implements adaptive grids for robust quantum wave packet dynamics and optimized sampling.

Main Results:

• Accurate treatment of quantum dynamical effects, including zero-point energy, tunneling, and over-barrier reflections.
• Simultaneous handling of electronic degrees of freedom using density functional theory (DFT) approximations.
• Benchmark calculations on proton transfer systems demonstrate high accuracy compared to exact methods.

Conclusions:

• The presented methodology offers an efficient and accurate approach for simulating coupled electron-nuclear dynamics.
• This method provides a robust tool for studying quantum phenomena in chemical systems.
• The approach is validated by benchmark calculations, showing good agreement with exact results.