Photoinduced reactions attract interest due to their basic science importance and broad applications. Photochemical processes involve broad ranges of time scales, sizes of involved molecules, and intensities of inducing electromagnetic radiation. Utilization of high intensity laser fields opens an opportunity to facilitate reactions with substantial activation energy, not available in conventional chemistry. Here, we will present a recently developed density functional theory (DFT) based time-dependent excited-state molecular dynamics (TDESMD) methodology to model photoinduced chemical reactions. The TDESMD algorithm is implemented using Rabi oscillations and principles similar to trajectory surface hopping, with a mid-intensity field approximation. The leading order process is represented by the molecule undergoing cyclic excitations and de-excitations. During excitation cycles, the nuclear kinetic energy is accumulated to overcome the reaction barriers. The dynamical formation of multiple products is observed in TDESMD trajectories. Applications of TDESMD include photofragmentation of gas-phase metal-organic complexes and small organic molecules as well as photopolymerization of inorganic monomers. In photofragmentation, one reactant molecule is converted into several product molecules of smaller molecular mass. In photopolymerization, several reactant molecules convert into one product molecule of larger molecular mass. The applied results are related to fabrication of nanostructured materials for optoelectronics applications.

Modeling photoinduced chemical reactions with time-dependent excited-state molecular dynamics

256th National Meeting (2018)

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