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Theoretical study of the electronic structure of diazomethane - I. The dissociation process CH2N2→CH2 + N2 in point group C2 v Symmetry

par Liévin, Jacques ;Verhaegen, Georges
Référence Theoretica chimica acta, 42, 1, page (47-65)
Publication Publié, 1976-03

Article révisé par les pairs

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Résumé :

Ab initio calculations of the dissociation process CH2N2 → CH2 + N2 are presented. Calculations were made on the ground 1A1 state as well as on the first few excited states (3B1, 1B1, 1A1*) necessary to the description of the dissociation mechanism in point group C2 v symmetry. The variation of energy was determined as a function of the parameters RCH-RNN and θHCH at several RCN values. Most results were obtained by using a basis set of Gaussian lobe functions contracted to "double-zeta" accuracy. A few calculations were made with the addition of polarization functions on all centers. The equilibrium geometry of the ground state, determined from coupled quadratic equations in the molecular parameters, is in satisfactory agreement with experimental values. The dissociation paths on the potential energy surfaces were determined. The locus of intersection points of the two 1A1 states is described; the avoided crossing of the two potential surfaces was determined from CI calculations based on an "intermediate" Hamiltonian. The geometric and electronic rearrangements due to dissociation as well as the bonding characteristics of the orbitals are discussed. The dissociation energy of the molecule (D00(CH2N2)) is calculated to be 0.91 eV. Finally, the term energy of the 1A1 state of CH2 is predicted to be 0.49 eV. © 1976 Springer-Verlag.