The Vibration-Rotation-Tunneling Spectrum of the Polar and T-Shaped-N-in Isomers of (NNO)₂
In this paper we report transition frequencies and line strengths computed for bright states of the NNO dimer. We use a previously reported potential obtained from explicitly correlated coupled-cluster calculations and fit using an interpolating moving least-squares method. The rovibrational Schroedinger equation is solved with a symmetry adapted Lanczos algorithm and an uncoupled product basis set. All four inter-molecular coordinates are included in the calculation. We propose two tools for associating rovibrational wavefunctions with vibrational states and use them to find polar-like and T-shaped-N-in-like rovibrational states. The first tool uses a re-expansion of the rovibrational wavefunction in terms of J = 0 eigenfunctions. The second uses intensities. Calculated rotational transition frequencies are in very close agreement with experiment.
X. Wang et al., "The Vibration-Rotation-Tunneling Spectrum of the Polar and T-Shaped-N-in Isomers of (NNO)₂," Journal of Molecular Spectroscopy, vol. 268, no. 1-2, pp. 53-65, Elsevier, Jul 2011.
The definitive version is available at https://doi.org/10.1016/j.jms.2011.03.017
Keywords and Phrases
Basis sets; Coupled-cluster calculations; Lanczos algorithm; Line strength; Moving least squares; Re-expansion; Rotational transition frequencies; Rovibrational intensities; Rovibrational spectroscopy; Rovibrational state; Schroedinger equations; Tool use; Transition frequencies; Van der waals molecules; Vibrational state; Algorithms; Dimers; Eigenvalues and eigenfunctions; Least squares approximations; Schrodinger equation; Van der Waals forces; Isomers; Lanczos algorithm; Rovibrational intensities; Rovibrational spectroscopy; Van der Waals molecules
International Standard Serial Number (ISSN)
Article - Journal
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