Rothe Time Propagation for Coupled Electronic and Rovibrational Quantum Dynamics.

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Physics

Background:

• Simulating molecular systems under intense laser fields requires methods beyond the standard Born-Oppenheimer approximation.
• Accurate modeling of coupled electronic-nuclear dynamics is crucial for understanding light-matter interactions at the attosecond timescale.

Purpose of the Study:

• To present a proof-of-principle study on time-propagating wave packets using linear combinations of explicitly correlated Gaussians (ECGs).
• To validate the ECG approach by comparing its results to highly accurate grid-based propagation methods for model systems.

Main Methods:

• Utilized Rothe's method for time propagation of wave packets expanded in ECG basis functions.
• Employed basis sets of ECGs with optimizable complex exponential parameters.
• Simulated two model systems: a nucleus in a Morse potential and an electron in a Coulomb-like potential, subjected to intense laser pulses.

Main Results:

• The ECG-based time propagation method closely reproduced virtually exact results from grid-based simulations for both model systems.
• Demonstrated the accuracy and viability of using ECGs for simulating coupled nuclear-electronic dynamics.

Conclusions:

• Explicitly correlated Gaussians (ECGs) provide a powerful and accurate alternative to purely grid-based methods for simulating complex molecular dynamics driven by intense laser fields.
• The presented approach offers a promising direction for future research in attosecond science and strong field physics.