We utilize the exact factorization of the electron-nuclear wave function [Abedi et al., PRL 105 123002 (2010)] to illuminate several aspects of laser-driven molecular dynamics in intense femtosecond laser pulses. Above factorization allows for a splitting of the full molecular wave function and leads to a time-dependent Schrödinger equation for the nuclear subsystem alone which is exact in the sense that the absolute square of the corresponding, purely nuclear, wave function yields the exact nuclear N-body density of the full electron-nuclear system. As one remarkable feature, this factorization provides the exact classical force, the force which contains the highest amount of electron-nuclear correlations that can be retained in the quantum-classical limit of the electron-nuclear system.
We re-evaluate the classical limit of the nuclear Schrödinger equation from the perspective of the exact factorization, and address the long-standing question of the validity of the popular quantum-classical surface hopping approach in laserdriven cases. In particular, our access to the exact classical force allows for an elaborate evaluation of the various and completely different potential energy surfaces frequently applied in surface hopping calculations.
The highlight of this work consists in a generalization of the exact factorization and its application to the laser-driven molecular wave function in the Floquet picture, where the molecule and the laser form an united quantum system exhibiting its own Hilbert space. This particular factorization enables us to establish an analytic connection between the exact nuclear force and Floquet potential energy surfaces.
Complementing above topics, we combine different well-known and proven methods to give a systematic study of molecular dissociation mechanisms for the complicated electric fields provided by modern attosecond laser technology.:Contents
Introduction
1 The exact factorization of time-dependent wave functions
1.1 Concern and state of the art
1.2 The exact factorization of the electron-nuclear wave function
1.3 The generalized exact factorization
1.4 The exact factorization for coupled harmonic oscillators
1.5 The exact factorization for a single particle with spin
1.6 The exact factorization of the laser-driven electron-nuclear wave function in the Floquet picture
1.7 Summary and conclusion
2 Quantum-classical molecular dynamics from an exact factorization perspective
2.1 Concern and state of the art
2.2 The exact nuclear TDSE
2.3 The Wigner-Moyal equation for the nuclear TDSE and its classical limit
2.4 The Bohmian formulation of the nuclear TDSE and its classical limit
2.5 Comparative calculations
2.5.1 Scenario 1: stationary states
2.5.2 Scenario 2: laser-driven dynamics
2.6 Summary and conclusion
3 Surface hopping in laser-driven molecular dynamics
3.1 Concern and state of the art
3.2 Surface hopping
3.3 Quantum-classical dynamics on the EPES
3.4 The benchmark model and its potential energy surfaces
3.5 Surface hopping in laser-driven molecular dynamics
3.6 Summary and conclusion
4 Beyond the limit of the Floquet picture: molecular dissociation in few-cycle laser pulses
4.1 Concern and state of the art
4.2 Theoretical few-cycle pulses
4.3 Calculation of dissociation probabilities
4.4 Dissociation in few-cycle pulses
4.4.1 Dissociation in half-cycle pulses
4.4.2 Dissociation in few-cycle pulses
4.5 Dissociation in realistic attosecond pulses
4.6 Summary and conclusion
Outlook
Appendices
A List of abbreviations
B Numerical details
C Calculating electronic observables within quantum-classical molecular dynamics
D Ionization in few-cycle pulses
E Modeling an optical attosecond pulse
Bibliography
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:32750 |
| Date | 19 January 2019 |
| Creators | Fiedlschuster, Tobias |
| Contributors | Strunz, Walter, Gross, E. K. U., Schmidt, Rüdiger, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/acceptedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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