The collisional energy transfer reaction, O('D) + N2 -0(3P) + N2(v,/), has been studied by means of the ab initio MO and quasi-classical trajectory calculations. The ab initio MO calculations showed that the singlet surface [0('D)+N2] is composed of the attractive potential curve where a strongly bound intermediate complex N20 is formed in the potential basin, whereas the triplet surface [0(3P)+N2] is composed of the repulsive shape. Both surfaces were crossed at region of around r(0-N) = 1.9 Á and formed the seam of the conical intersection. By using the fitted ab initio PESs, three-dimensional surface-hopping trajectory calculations are performed. The calculated rotational and vibrational state distributions of the product N2-(v,J) were composed of two components due to the contributions from both direct and complex channels. The branching ratio of direct channel to complex one increased linearly with collision energy. This is due to the fact that number of trajectories via complex channels is significantly diminished with collision energy because of less contribution from complex channels at higher collision energy. The mechanism of the energy transfer was discussed on the basis of the theoretical results.

The energy transfer process of translationally hot oxygen atom O(1D) by inelastic collision with N2 molecule, fast O(1D) + N2 → slow O(1D) + N2(v,J), has been studied by means of quasi-classical trajectory calculations on the ab initio fitted potential energy surfaces (PESs). The surface hopping procedure was included in the trajectory calculations by the Landau−Zener model in order to consider contribution from the reactive trajectories, i.e., the electronic energy transfer process O(1D) + N2 → O(3P) + N2(v,J). Inelastic collisions occurring on 1A‘ and/or 3A‘ surfaces were only considered in the present study. The results suggest that the cross section for the translational energy transfer process increases with increasing collision energy. Efficiency of the energy transfer from translational to internal modes by a collision was calculated to be 0.45 at a collision energy of 10.0 kcal/mol. The energy relaxation processes of translationally hot O(1D) in the upper stratosphere are discussed on the basis of these theoretical results.

SUMMARYThe geometrical structure and vibrational modes of the complex formed between the copper atom and NO molecule for the ground state have been studied by means of an ab initio MO method. The ground and low-lying electronic states were determined by using the singly excited configuration interaction (CI) calculations. The bent structure with a Cu-N-O angle of 117• is obtained as the most stable form of the complex at the MP2/6-311G* level.

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