Quantum-classical dynamics of vibration-induced autoionization in molecules

Area of Science:

• Physical Chemistry
• Quantum Mechanics
• Chemical Physics

Background:

• Molecular anions can undergo autoionization, a process where an electron is ejected due to internal energy.
• Simulating these dynamics requires accurate treatment of quantum and classical aspects, including electron detachment.

Purpose of the Study:

• To introduce a novel quantum-classical surface hopping method for simulating vibration-induced autoionization in molecular anions.
• To provide a theoretical framework for understanding the dynamics of electron ejection and subsequent molecular rearrangements.

Main Methods:

• Utilizing a quantum-classical surface hopping approach to propagate classical trajectories on quantum potential energy surfaces.
• Incorporating autoionization via transitions to discretized continuum states, driven by electronic state couplings.
• Developing a discretization scheme and formulas for calculating bound-free electron state couplings.

Main Results:

• The method successfully simulates autoionization dynamics in vinylidene anion, an isomer of acetylene.
• Provides insights into the timescale of autoionization, electron energy and angular distributions.
• Identifies molecular structural changes, including reduced C-C bond lengths and T-like conformations.

Conclusions:

• Autoionization plays a crucial role in driving the isomerization of vinylidene anion to acetylene.
• The developed method offers a powerful tool for studying complex dynamics in molecular anions.
• Results correlate well with available experimental data for vinylidene anion.