Nonadiabatic wavepacket dynamics

One can also ask about the relationship of the FMS method, as opposed to AIMS, with other wavepacket and semiclassical nonadiabatic dynamics methods. We first compare FMS to previous methods in cases where there is no spawning, and then proceed to compare with previous methods for nonadiabatic dynamics. We stress that we have always allowed for spawning in our applications of the method, and indeed the whole point of the FMS method is to address problems where localized nuclear quantum mechanical effects are important. Nevertheless, it is useful to place the method in context by asking how it relates to previous methods in the absence of its adaptive basis set character. There have been many attempts to use Gaussian basis functions in wavepacket dynamics, and we cannot mention all of these. Instead, we limit ourselves to those methods that we feel are most closely related to FMS, with apologies to those that are not included. A nice review that covers some of the... 

Summary. An effective scheme for the laser control of wavepacket dynamics applicable to systems with many degrees of freedom is discussed. It is demonstrated that specially designed quadratically chirped pulses can be used to achieve fast and near-complete excitation of the wavepacket without significantly distorting its shape. The parameters of the laser pulse can be estimated analytically from the Zhu-Nakamura (ZN) theory of nonadiabatic transitions. The scheme is applicable to various processes, such as simple electronic excitations, pump-dumps, and selective bond-breaking, and, taking diatomic and triatomic molecules as examples, it is actually shown to work well. 

Fig. 8. Adiabatic electronic populations of the higher JT sheet of the ground state manifold of H3, as obtained from 3D wavepacket dynamical calculations. Five different upper-cone vibrational states are employed in the calculation as initial states, which are indicated through the different line types (see legend for their assignment). The extremely fast decay, with lifetimes of only 3-6 fe, demonstrates the exceedingly strong nonadiabatic coupling effects in this system. This amounts to a very large homogeneous (lifetime) broadening of these levels which causes them to be absent in the spectra of Fig. 7. Note the mode-specificity of the lifetimes (see text).

Chapter 7 continues the presentation of nonadiabatic electron wavepacket d mamics as applied in various chemical reactions, mainly in electronically excited states. Quantization the branching paths (non-Born-Oppenheimer paths) will be also discussed. Likewise, in Chap. 8, the electron wavepacket dynamics is considered for molecules placed in laser fields. In addition to the ordinary nonadiabatic transitions due to the Born-Oppenheimer approximation, novel nonadiabatic transitions due to optical interactions appear to need special cares. This chapter is to be continued to future studies of laser design of electronic states and concomitant control of chemical reactions. 

Nonadiabatic Electron Wavepacket Dynamics in Path-branching Representation... 

Summary of the standard nuclear wavepacket dynamics for nonadiabatic transitions... 

Nonadiabatic Electron Wavepacket Dynamics in Path-branching Representation 197 6.2.1.4 Phase-space averaging vs. force averaging... 

We have thus made up electron wavepacket dynamics nonadiabatically coupled with branching nuclear paths within the above quantum-classical... 

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