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Development of Microscopic Models for Characterizing the Effects of Dissipation on the Quantum Control of Chemical Reactions

Subject Area Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
Term from 2012 to 2018
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 219003971
 
Final Report Year 2019

Final Report Abstract

We develop atomistic quantum mechanical models based on a balanced system-environment separation for characterizing ultrafast processes in nanostructured materials. Particular emphasis is placed on the role played by energy exchange between the systems and their respective environment. The most important advances can be summarized as follows: 1. Efficient simulation of ultrafast electron dynamics at the nanoscale: • We developed wave function based methods for ultrafast electron dynamics of nanostructures in intense laser fields. The methods retains the advantages of density functional theory and of time-dependent configuration interaction methodologies, while representing coupling with the environment with stochastic kick operators. • We developed a theory of non-adiabaticity to characterize energy exchange in semiconductor nanostructures. The model is reminiscent of the 3D Fermi liquid theory for metallic environments. 2. Imaging electron dynamics using transient electronic flux density maps: • We developed numerical tools to extract mechanistic information from the wave packet dynamics using electronic flux density maps. These were used to describe laser-induced attosecond charge migration in molecular systems, as well as the injection process in dye-sensitized solar cells and the current through nanojunctions. 3. Quantum dynamics at surfaces: • We developed numerical tools for high-dimensional spectroscopy at surfaces, and for quantum scattering from metals. These will help assess the importance of energy quantization in elementary surface reactions, with potential implication in heterogeneous catalysis. 4. Revealing the mechanisms at work in single atom catalysis: • We investigated the co-adsorption behaviour of oxygen and carbon monoxide on gold, silver, and copper atoms on magnesium oxide surfaces, with respect to their inertness in heterogeneous catalysis. We demonstrated that surface reparation prevents catalytic oxidation on defective surfaces, and that only gold offers sufficient support for oxygen bond breaking. 5. Atomistic manipulation of adsorbates at metallic surfaces: • We developed a unifying theory of non-adiabaticity for adsorbates at metallic surfaces, which can also explain the dynamical behaviour upon excitation using scanning tunnelling microscopy (STM). • We explained the experimentally observed STM-induced conformational changes in H/Pd(111), with possible implications for hydrogen storage. We provided mechanistic insight into an STM-induced tautomerization dynamics, revealing the role played by intermode coupling. These simulations demonstrate that STM excitation on metals can be rationalized as a quasi-thermal theory.

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