Ultrafast molecular currents

When a molecule is irradiated by an intense laser pulse, the high-lying valance electrons (e.g. in the highest-occupied molecular orbital (HOMO)) can be photoionized from the system, leaving an excited hole wavepacket behind. Since the hole is not an eigenstate of the cation, ultrafast charge migration (CM) can occur whereby the remaining electrons rearrange themselves by moving around the molecule. In certain conditions, this can lead to a coherent motion of charges around the molecule that persists for many femtoseconds. This effect is intimately connected with the physical process of radiation damage in bio-molecules, as well as charge transfer in electronic systems. To date, it remains not fully understood with multiple open questions: Under which conditions can CM transpire? How does CM depend on the physical and chemical properties of the molecule? and on the laser radiation regime? What is the role of electronic correlations? And of nuclei motion (electro-vibrational coupling)?

We aim to develop a complete theoretical picture for CM processes by combining ab-initio methodologies based on TDDFT, and model Hamiltonians, addressing the above questions. We develop theoretical methods for describing CM, study the fundamental physical mechanisms at play, develop spectroscopy techniques for probing CM, and control methods for tailoring CM as well as any radiation emitted from the system (such as magnetic fields).