In this proposal we will study matter under extreme conditions of very strong electromagnetic laser fields. Due to the high intensities and extremely short timescales involved, the interaction of matter with intense laser fields holds the key to fundamental questions such as: How does an electron migrate in a photosynthetic molecule?How are holes created and dissipated in a solid?How does a metal melt in real time? The answer to such questions will lead not only to a better understanding of how matter evolves in this extreme regime, but also holds the promise of steering electron dynamics in real time with attosecond precision. This will have major repercussions in both fundamental and applied science, as electrons contribute to the breaking or making of chemical bonds, and are responsible for energy transport in biomolecules, solids and nanostructures. This implies an unprecedented control in light-harvesting processes and electron motion in electronic devices. In recent years, considerable progress has been made in the understanding of the attosecond dynamics in atoms and small molecules, both theoretically and experimentally. However, the modeling of complex systems in this regime poses a far greater challenge. An appropriate treatment of electron-electron correlation, excitation, migration and the coupling of internal degrees of freedom goes far beyond the present capabilities of the existing strong-field theories, which impose a series of major restrictions on the residual binding potentials. Ab-initio approaches, on the other hand, are inapplicable to large systems, as the numerical effort increases exponentially with the degrees of freedom involved.
In order to face this challenge, one must develop novel theoretical approaches for multi-electron systems in strong fields that (i) do not suffer from the above-mentioned "exponential wall"; (ii) account for the core dynamics and electron-electron correlation; (iii) do not impose major restrictions on the binding potentials in the system; (iv) provide an intuitive physical picture of the phenomena to be studied in terms of electron orbits. With this in mind, we have assembled a multi-institutional, interdisciplinary team, composed of leading experts in the UK whose background encompasses quantum chemistry, strong-field and condensed-matter physics, which is unified by using trajectory based methods in quantum dynamics. Our main objective is to develop the above-mentioned approaches.
In this project, we intend to extend and combine methods from quantum chemistry and condensed-matter physics with a wide range of applicability to many-body systems, such as the Coupled Coherent State (CCS) approach or the time-dependent density functional theory (tddft), to describe attosecond multielectron dynamics. We will apply such methods to concrete physical systems with increasing degree of complexity, such as one-, two- and multielectron atoms, diatomic and polyatomic molecules. The CCS will both be extended to multielectron systems, and combined with the tddft in hybrid approaches. Whenever possible, we will also develop novel analytic, or semi-analytic theories.
In the first part of this project, we will focus on one- and two electron systems and the interplay between the laser field and the binding potentials. Subsequently, we will model and study the core dynamics in multielectron systems. A detailed assessment of the differences, similarities and limitations of each approach will be made. Throughout, we will compare our results to the pioneering experiments at the Imperial College London, on HHG in organic molecules, and at the MPQ, Munich, on laser-induced nonsequential double ionization. This proposal will provide a unique set of tools worldwide for modeling attosecond multielectron dynamics, and pave the way towards the ultimate goal of controlling attosecond processes in real time. This will break new ground in physics, chemistry, biology and applied science.
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