Coherent electron dynamics are an important but poorly understood ultrafast light-matter interaction where a short laser pulse leaves the system in a superposition of states. The resulting electron motion occurs at the time scale of hundreds of attoseconds, i.e., an order of magnitude faster than nuclear motion, and is a result of quantum coherences and electron correlation. Simulating these processes is vital to understanding and ultimately directing the initial steps of photochemistry and light harvesting. First principles simulations can be very challenging as intense fields require a non-perturbative treatment, and time propagation approaches can be prohibitively expensive for many wavefunction-based methods. This is compounded for systems with a large density of states where many states can be involved in the dynamics and computation of transient spectra can be difficult.<br/>In this talk, I will discuss time-dependent density functional theory (TDDFT) methodologies for simulating coherent dynamics in molecules and materials including formal considerations (e.g., the role of self-interaction), approaches for extracting and quantifying dynamical modes of interest from a dense manifold of excitations, and mechanistic interpretations. One focus will be on strong-field ionization-triggered attosecond charge migration in small and medium-sized molecules (carbonyl sulfide, iodoacetylene, nitrosobenzene, hexatriene), where the coherent hole dynamics have a relatively simple “chemical” interpretation as a time evolving superposition of Lewis dot resonance structures. The second focus will be on attosecond electron dynamics in solids simulated using bulk-mimicking finite clusters. Here, alternatives to Fourier transforms allow for rapid computation of transient X-ray absorption spectra.<br/><br/>

Coherent electron dynamics in systems with a high density of states

2019 Spring National Meeting

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