Determination of vibrational energy levels and parallel band intensities of 12C16O2 by Direct Numerical Diagonalization

Abstract The Direct Numerical Diagonalization (DND) technique has been applied to the principal symmetric species of carbon dioxide. A three-dimensional formulation of the DND method has been implemented as a first step in using the method to calculate properties of simple polyatomic molecules. Recent high-resolution observations of both line positions and intensities have been incorporated into the method to yield new values for the potential function and the dipolar coefficients. The results are compared with the potential functions calculated by earlier DND efforts as well as the contact transformation approach. The results are also discussed in terms of the effects of truncation errors caused by the use of finite matrices to represent the Hamiltonian operator. The resulting eigenvectors have been used to determine a dipole moment function from 21 observed band intensity values. This dipole moment function in turn has generated a large list of band intensity estimates for 12 C 16 O 2 parallel bands which are being used to update the AFGL line parameter compilation. This list represents the first published set of band intensity values derived from a consistent quantum mechanical model for a linear polyatomic molecule.

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