Potential energy function and vibrational states of N2CO+

M. Hochlaf (1) , Céline Léonard (2) , E. E. Ferguson , P. Rosmus , E. A. Reinsch , S. Carter , N. C. Handy

1 LCT - Laboratoire de Chimie Théorique
2 LaM - Laboratoire de Mécanique

A six-dimensional potential energy function (PEF) for the electronic ground state of N2CO+ (X (2)A(')) has been generated by electronic structure calculations using the restricted open shell coupled cluster RCCSD(T) approach. The ion has a planar trans equilibrium structure with: R-NN=1.106 Angstrom, R-NC=1.905 Angstrom, R-CO=1.127 Angstrom, theta(NNC)=175.3 degrees, and theta(NCO)=129.1 degrees. Variational calculations of the vibrational states (J=0) have yielded the following anharmonic wavenumbers for the fundamentals: nu(1) (NN stretch) 2287.2, nu(2) (CO stretch) 2071.0, nu(3) (CN stretch+NCO bend) 546.9, nu(4) (CN stretch+NCO bend) 215.2, nu(5) (in-plane NNC bend) 123.4, nu(6) (out-of-plane NNC bend) 133.8 (all values are in cm(-1)). For fixed equilibrium coordinates except one, the barriers to linearity have been calculated to be 8 cm(-1) for the NNC and 2260 cm(-1) for the NCO moieties, the torsional barrier to be 35 cm(-1). It has been found that the nu(3) and nu(4) modes are strongly coupled, the in-plane nu(5) and out-of-plane nu(6) bending modes possess an inverse anharmonicity and fall into clusters. Using complete active space self-consitent-field CASSCF approach on the collinear cuts of the PEF for low-lying excited states several conical intersections between the (2)Pi and the (2)Sigma(+) states have been located. (C) 1999 American Institute of Physics. [S0021- 9606(99)30135-5].

Domaines: Physique Classique [physics.class-ph]

M. Hochlaf, Céline Léonard, E. E. Ferguson, P. Rosmus, E. A. Reinsch, et al.. Potential energy function and vibrational states of N2CO+. Journal of Chemical Physics, 1999, 111 (11), pp.4948--4955. ⟨10.1063/1.479754⟩. ⟨hal-00693857⟩