Potential energy surfaces results analysis

The lowest-lying potential energy surfaces for the 0(3P) + CH2=C=CH2 reaction were theoretically characterized using CBS-QB3, RRKM statistical rate theory, and weak-collision master equation analysis using the exact stochastic simulation method. The results predicted that the electrophilic O-addition pathways on the central and terminal carbon atom are dominant up to combustion temperatures. Major predicted end-products are in agreement with experimental evidence. New H-abstraction pathways, resulting in OH and propargyl radicals, have been identified.254... 

The present analysis relies on - and extends - the comprehensive theoretical study of Refs. [23,24] on the multi-state interactions in the manifold of the X — E states of Bz+. Like this recent work, it utilizes an ab initio quantum-dynamical approach. In Refs. [23,24] we have, in addition, identified strong coupling effects between the B — C and B — D electronic states, caused by additional conical intersections between their potential energy surfaces. A whole sequence of stepwise femtosecond internal conversion processes results [24]. Such sequential internal conversion processes are of general importance as is evidenced indirectly by the fluorescence and fragmentation dynamics of organic closed-shell molecules and radical cations [49,50]. It is therefore to be expected that the present approach and results may be of relevance for many other medium-sized molecular systems. 

The VB simplified model of ground-state potential energy surface H3 system considered as transition state and stabilization valleys of the H + H2 reaction is also an early problem, belonging to the history of physical chemistry under the name London-Eyring-Polanyi-Sato (LEPS) model that continues to serve as basis of further related developments [17,18], The actual analysis is a new a focus on the JT point of this potential energy surface able to absorb results of further renewed CASCCF type calculations on this important system. 

Another important topographical feature often arises from the fact that polyatomic potential-energy surfaces may intersect in regions of the configuration space where the corresponding wave functions belong to the same (spatial and spin) symmetry.34-39 The importance of this result in the context of the present work justifies a brief analysis of its essential aspects. 

The reliability of high-dimensional quantum calculations based on ab initio potential energy surfaces is also demonstrated in Fig. 6, where the sticking probability of H2/Cu(l 0 0) obtained by sixdimensional wave packet calculations [32] is compared to experimental results derived from an analysis of adsorption and desorption experiments [27]. The measured experimental sticking probabilities and, via the principle of detailed balance, also desorption distributions had been fitted to the following analytical form of the vibrationally resolved sticking probability as a function of the kinetic energy ... 

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