Elucidation of the Ro-Vibrational Band Structures in the Silicon Tetrafluoride Spectra from Accurate Ab Initio Calculations

We report the construction of comprehensive line lists for the three stable isotopologues of silicon tetrafluoride (²⁸SiF₄, ²⁹SiF₄, and ³⁰SiF₄) using a new effective Hamiltonian and dipole moment model built from accurate ab initio potential energy and dipole moment surfaces developed in this work. The vibrational energy levels were grouped into a series of polyads up to P_max = 19, while the ro-vibrational energy levels were computed up to J_max = 99. Each line list covers the spectral range 0–2500 cm⁻¹ and contains almost 500 million transitions at T = 296 K, with each being generated from 685 vibrational states and sub-states. Most of the cold and hot band transitions computed in this work were not available in the literature beforehand. The absorption cross-sections computed from the produced line lists were successfully validated by direct comparison with the experimental data measured by Pacific Northwest National Laboratory at room temperature. Most of the ro-vibrational band structures observed in the experimental spectra can now be elucidated using the line lists proposed in this work.