Photophysics electronic wave

Computationally, the present approach rests on the QVC coupling scheme in conjunction with coupled-cluster electronic structure calculations for the vibronic Hamiltonian, and on the MCDTH wave packet propagation method for the nuclear dynamics. In combination, these are powerful tools for studying such systems with 10-20 nuclear degrees of freedom. (This holds especially in view of so-called multilayer MCTDH implementations which further enhance the computational efficiency [130,131].) If the LVC or QVC schemes are not applicable, related variants of constructing diabatic electronic states are available [132,133], which may extend the realm of application from the present spectroscopic and photophysical also to photochemical problems. Their feasibility and further applications remain to be investigated in future work. 

Photochemistry is inherently related to photophysics, the study of those radiative and nonradiative processes that convert one electronic state into another electronic state without chemical change. Central to both photochemistry and photophysics is the classification of UV-vis radiation in terms of its energy. Because electromagnetic radiation is quantized, it has properties like those of a particle, and a mole of photons is called an einstein. Electromagnetic radiation also has the properties of a wave, and equation 12.1 gives the relationship between the energy of UV-vis radiation in kcal/mol and its wavelength in run. ... 

It should be stressed that the wave-packet picture of photophysical relaxation and photochemical reaction dynamics described in this chapter is substantially different from the traditional concepts in this area. In contrast to the established picture of radiationless transitions in terms of interacting tiers of zero-order molecular eigenstates, the dynamics is rationalized in terms of local properties of PE surfaces such as slopes, barriers and surface intersections, a view which now becomes widely accepted in photochemistry. This picture is firmly based on ah initio electronic-structure theory, and the molecular relaxation d3mamics is described on the basis of quantum mechanics, replacing previously prevaUing kinetic models of electronic decay processes. Such a more detailed and rigorous description of elementary photochemical processes appears timely in view of the rich and specific information on ultrafast chemical processes which is provided by modern time-resolved spectroscopy. " ... 

Semiclassical Wave Packet Dynamics with Electronic Structure Computed on the Fly Application to Photophysics of Electronic Excited States in Condensed Phase. 

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