Theoretical rovibrational line intensities in the electronic ground state of ozone

Abstract

First-principles calculations of absolute line intensities and rovibrational energies of ozone (¹⁶O₃) are reported using potential energy and electric dipole moment functions calculated by the internally contracted MRCI approach. The rovibrational energies and eigenfunctions (up to about 8500 cm⁻¹ and J = 64) were obtained variationally with an exact Hamiltonian in internal valence coordinates. More than 4.8 × 10⁶ electric dipole transition matrix elements were calculated for the absolute rovibrational line intensities. They are compared with the values of the HITRAN database. The purely rotational absolute line intensities in the (000) state and the rovibrational intensities for the (001)–(000) band agree to within about 0.3 to 1% for the (010)–(000) band to within about 3 to 4%. Excellent agreement with experiment is also achieved for low-lying overtone and combination bands. Inconsistencies are found for the (100)–(000) band overlapping with the antisymmetric stretching fundamental and also for the (002)–(000) antisymmetric stretching overtone. The generated dipole moment function can be used for predicting the absorption intensities in any of the heavier isotopomers, hot bands or the rates of spontaneous emission.