Calculations of NO2+at HF, CBS-4, CASSCF, MBPT(2), MBPT(3), and MBPT(4) theory levels, using 3-21G and 6-31G(d) basis sets, found two C2Vstructures along with the linear geometry. Computations using MBPT(2) and CCSD(T) approaches and the aug-cc-pvtz basis set confirmed these results. Harmonic vibrational frequency calculations, performed with MBPT(2) and CCSD(T) theories, indicated that the linear structure was the global minimum while one of the bent structures (∠ONO=80°) was a higher energy local minimum. The second C2Vstructure (∠ONO=45°) exhibited a large imaginary vibrational frequency along the asymmetric stretching (B2) mode, indicating its saddle point nature. © 2001 Elsevier Science B.V.
Füzéry, A. K., Burcl, R., Torday, L. L., Császár, P., Farkas, O., Perczel, A., … Csizmadia, I. G. (2001). Can NO2+exist in bent or cyclic forms? Chemical Physics Letters, 334(4–6), 381–386. https://doi.org/10.1016/S0009-2614(00)01447-0