Wavepacket theory

Pollard W T, Lee S-Y and Mathies R A 1990 Wavepacket theory of dynamic absorption spectra in femtosecond pump-probe experiments J. Chem. Phys. 92 4012... 

Balint-Kurti, G.G., Wavepacket theory of photodissociation and reactive scattering, Adv. Chem. Phys., (irr press). 

The electron current within a molecule driven by an intense laser field should generate induced electromagnetic field. These in turn will bring about the nontrivial secondary effects [39,213,298,299,334,488]. The more intense external field is, the more prominent these secondary effects should be. However, they can be studied only by solving the coupled equations of quantum electronic wavepacket and the Maxwell equations in a self-consistent maimer [249]. To successfully achieve this project, a very good theory for nonadiabatic electron wavepacket theory must be constructed first. 

Although this book attempts to guide readers to modern nonadiabatic electron wavepacket theory (both in the presence and absence of external laser fields), we should first review the traditional theories, which have led the study of nonadiabatic transitions for a long time. Our motive for reviewing time-honored theories is not a historical interest but to help readers to understand fundamental ideas in the nonadiabatic dynamics, and therefore the list of the theories presented here is far from perfect. More complete reviews are already available in Refs. [28, 84, 85, 117, 178, 198, 291, 295]. 

As illustrated above, nonadiabatic dynamics exhibits vividly how electrons move in and between molecules. Complex natural orbitals, in particular SONO in the present case, clearly illustrate how the electronic wavefunction evolves in time. In addition to the time scale, the driving mechanism for the electron migration has also been illustrated. By clarifying such complex electron behavior, not available using stationary-state quantum chemistry, our understanding of realistic chemical reactions is greatly enhanced. As a result, it has clearly been shown that nonadiabatic electron wavepacket theory is invaluable in the analysis of non-rigid and mobile electronic states of molecular systems. 

Fig. 7.33 Snapshots of the dynamics of the unpaired electron density arising from the semicalssical Ehrenfest electron wavepacket theory along the reaction path of Fig. 7.30. (a) the initial stage of tt — tt optical transition, (b) at the moment of electron transfer from phenol to aimnonia clnster. (c) and (d) show further fluctuation within the ammonia cluster. (Reprinted with permission from K. Nagashima et al., J. Phys. Chem. A 116, 11167 (2012)).

One possible way to treat such a case is to use an approximated approach of the nonadiabatic electron wavepacket theory, the phase-space averaging and natural branching (PSANB) method [493], or the branching-path representation, in which the wavepackets propagate along non-Born-Oppenheimer branching paths. 

This is the generalization of the electron wavepacket theory to the dynamics in an optical field [492]. Note that the second derivative coupling elements, ... 

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