Intersections, conical nonadiabatic effects

The topography of a conical intersection affects the propensity for a nonadiabatic transition. Here, we focus on the essential linear tenns. Higher order effects are described in [10]. The local topography can be detennined from Eq. (13). For T] = 3, Eq. (13) becomes, in orthgonal intersection adapted coordinates... 

Since we are interested in electronic phase effects accompanying adiabatic nuclear excursions, and are considering motion near a conical intersection, we must specify the conditions under which adiabaticity obtains. A wave packet moving on one of the excited state potential surfaces will not undergo nonadiabatic transition to the other provided it is further from q = 0 than its width and that... 

We shall here discuss only the nonadiabatic effects due to the conical intersection between two adiabatic electronic states. By therefore considering only the electronic and vibrational motion, the molecular Schrddinger equation... 

The conical-intersection effects increase with the energy, up to their full development at about 16000 cm, where the density of the nonadiabatic levels is about four times larger than that at 10000 cm l and nearly all of them are vibradonally and/or vibronically mixed. For example, 5 and 64 states n> are strongly mixed, with... 

In the fourth part, we study the effect of Cl on IC. It was applied to study the TtTt ->nTT transition of the pyrazine molecule. In this nonadiabatic process, the Cl of the TCK and nir PESs is believed to play a major role in the nonadiabatic fs transition. In fact, the Cl has been widely proposed to play the key factor in an IC, and quantum trajectory calculations have been used to calculate the IC rates [45]. However, this method cannot properly take into account of the initial conditions of the population and coherence of the system created by the fs pumping laser. In this chapter, we propose to develop a method to calculate the IC with conical intersections. It should be known that for the IC between Si and So in most molecules (in these cases, the energy gap between and So is of several eV), the surface crossings do not take place due to the anharmonic effect in the two PESs. Thus, the Cl should not play any role in these cases. We have proposed one method to calculate the IC rate of mt of the pyrazine molecule. The... 

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