Vibrational energy spectrum of SO2 isotopologues
A.D. Bykov, B.A. Voronin
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: SO2, vibrational levels, isotopologue, perturbation theory
Abstract
The paper presents the results of calculating 10 the lowest vibrational energy levels of all 24 stable sulfur dioxide isotopologues. The calculations were performed using the ab initio potential energy function of the main isotopologue 32S16O2, the Rayleigh-Schrödinger perturbation theory of high orders and the Padé-Hermite series summation method. A numerical analysis of the series was performed, which showed that the perturbation series monotonically converge, but to obtain the energy levels of some vibrational states with an error of less than 1.0 cm-1, it is necessary to take into account the corrections of the 3rd-6th orders. The quadratic Padé-Hermite approximants give energy levels that coincide with high accuracy with the results of numerical diagonalization of the Hamiltonian matrix. A correction is proposed for calculating isotopic shifts, which gives a root-mean-square coincidence of 1.1 cm-1 with the experimental and calculated data by other authors. The calculation results can be used to solve various problems of atmospheric spectroscopy, astrophysics, geochemistry, and other fields of science related to the analysis of spectra of isotope-substituted molecules.
|
