Molecular Modes of Attosecond Charge Migration

Charge migration (CM) is a coherent mechanism in which a localized hole created by sudden ionization of a molecule travels across the molecular backbone in the time scale of a few hundred attoseconds. In this work, we use first-principles simulations to develop a set of heuristics for charge migration. Halogenated hydrocarbons are studied because they are promising targets for ionization-triggered charge migration experiments and they support the creation of a localized hole via strong-field ionization (SFI). Using constrained density functional theory (cDFT) to emulate SFI, a localized hole was created on the halogen followed by time dependent density functional theory (TDDFT) simulations. After which, we explored the relationship between obtained CM modes and molecules’ length, bond order, and halogenation. Our results show that the CM speed is largely independent of molecule length (~4Å/fs) and hole behaves like a particle as the atomic number of the halogen increases. These heuristics will be useful in identifying molecules and optimal CM detection methods for future experiments.