Molecular Modes of Attosecond Charge Migration

Area of Science:

• Computational chemistry
• Quantum mechanics
• Molecular dynamics

Background:

• Attosecond charge migration (CM) is a fundamental process in molecular systems.
• Understanding CM dynamics is crucial for controlling electron behavior in molecules.
• Halogenated hydrocarbons are promising candidates for studying ionization-triggered CM.

Purpose of the Study:

• To elucidate the modes of attosecond charge migration (CM) in halogenated hydrocarbon chains.
• To investigate the influence of molecular structure on CM dynamics.
• To provide heuristics for experimental identification of CM and suitable molecules.

Main Methods:

• First-principles calculations using constrained density functional theory (DFT).
• Time-dependent DFT to simulate the subsequent charge migration dynamics.
• Analysis of CM modes, frequency, speed, and dependence on molecular parameters.

Main Results:

• Observed low-frequency CM modes (approximately 1 eV) propagating across the molecule.
• CM speed (approximately 4 Å/fs) was largely independent of molecular length.
• CM speed decreased for triple-bonded compared to double-bonded molecules.
• Increased halogen mass led to more particle-like hole motion.

Conclusions:

• Low-frequency charge migration modes exist in halogenated hydrocarbons.
• Molecular structure, specifically bond order and halogen mass, significantly influences CM dynamics.
• The findings offer valuable insights for designing future experiments on attosecond charge migration.