A quantum and semiclassical study of dynamical resonances in the C+NO→CN+O reaction

Abstract

Accurate quantum mechanical reactive scattering calculations were performed for the collinear CϩNO→CNϩO reaction using a polynomial-modified London Eyring Polanyi Sato ͑PQLEPS͒ potential energy surface ͑PES͒, which has a 4.26 eV deep well in the strong interaction region, and a reference LEPS PES, which has no well in that region. The reaction probabilities obtained for both PESs show signatures for resonances. These resonances were characterized by calculating the eigenvalues and eigenvectors of the collision lifetime matrix as a function of energy. Many resonances were found for scattering on both PESs, indicating that the potential well in the PQLEPS PES does not play the sole role in producing resonances in this relatively heavy atom system and that Feshbach processes occur for both PESs. However, the well in the PQLEPS PES is responsible for the differences in the energies, lifetimes, and compositions of the corresponding resonance states. These resonances are also interpreted in terms of simple periodic orbits supported by both PESs ͑using the WKB formalism͒, to further illustrate the role played by that potential well on the dynamics of this reaction. The existence of the resonances is associated with the dynamics of the long-lived CNO complex, which is much different than that of systems having an activation barrier. Although these results were obtained for a collinear model of the reaction, its collinearly-dominated nature suggests that related resonant behavior may occur in the real world.

Classical and quantum dynamics of the O + CN reaction

“…Quantum effects were observed also by Abrol et al [10], who performed collinear time-independent quantum dynamics calculations on the C + NO reaction at low energies. It remains an open question as to whether quantum effects are also clearly visible in a three-dimensional treatment of the dynamics.…”

“…It is quite feasible that the differences would then be washed out when producing cross sections by averaging the results over many values of the total angular momentum (or the impact parameter). However, Abrol et al [10] performed 2D wave packet calculations on the C + NO reaction and suggested that the resonances they observed may survive in 3D calculations. They in fact speculated that the resonances would survive in the 'real world' and it would be fascinating if this could be investigated.…”

“…Recently Abrol and collaborators [10] performed 2D wave packet calculations for the collinear C + NO ! CN + O reaction, observing resonances.…”

Rotational excitation of HC3N by H2and He at low temperatures

“…The fine energy grid emphasizes the resonances for E < ∼ 10 cm −1 . these shape resonances reflect the trapping of the wave-packet between the inner repulsive wall and the outer centrifugal barrier, see , Abrol et al (2001). At energies higher than about 20 cm −1 above threshold, all cross-sections become smooth functions of the energy.…”

Statistical properties of quantum probability fluctuations in complex-forming chemical reactions

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The origin of the sharp fluctuations is rather well understood. The study of Smith life-time matrix 6,29,30 indeed reveals that fluctuations are resonance structures due to dense sets of metastable states above the dissociation limit of the intermediate complex. These structures are related to Ericson fluctuations, 31 first seen in nuclear reaction cross sections.…”