An a b i n i t i o investigation of the spectroscopic properties of ClF, ArF+, SF−, and ClO− in their ground electronic states

Abstract

The potential energy and electric dipole moment functions of the 26-electron species ClF, ArF+, SF−, and ClO− in their X 1∑+ electronic states have been calculated by the coupled electron pair approximation (CEPA) and singles and doubles configuration interaction (CI-SD) using a basis set of 101 contracted Gaussian-type orbitals. Potential energy functions have also been calculated by Mo/ller–Plesset fourth-order perturbation theory with single, double, and quadruple excitations (MP4SDQ) for all four species. Values of re and ωe calculated for the ClF molecule agree with experiment to within 0.004 Å and 16 cm−1, respectively, at the CEPA and MP4SDQ levels of approximation, and also when a size consistency correction was applied to the CI-SD energies [designated CI-SD(s)]. Predictions of rotational and vibrational spectra have been made for the isoelectronic ions, ArF+, SF−, and ClO−. The MP4SDTQ (MP4SDQ with the addition of triple substitutions) level of approximation was used to calculate dissociation energies for all four species and electron affinities for the radical precursors of the negative ions. From the CEPA potential energy and electric dipole moment functions, dipole moment matrix elements and infrared radiative transition probabilities have been predicted. Molar IR integrated absorption intensities for the fundamental transitions have been predicted to be 3065 cm2 mol−1 (ClF), 15 500 cm2 mol−1 (SF−), 835 cm2 mol−1 (ClO−), and 22.3 cm2 mol−1 (ArF+).