First-principles calculations of rovibrational energies, dipole transition intensities and partition function for ethylene using MULTIMODE

摘要

Large-scale, rovibrational variational calculations are performed for ethylene, using the potential energy surface published by Avila and Carrington [J. Chem. Phys. 135, 064101 (2011)10.1063/1.3617249]. Energies for J = 0 are in very good agreement with their benchmark results. Corresponding energies for J = 1 and J = 2 are also given. Calculations with a slightly reduced basis permit energies to J = 40, allowing a reliable determination of the partition function at 296 K. Using a new ab initio dipole moment surface, reported here, the infrared spectra of five dipole-allowed fundamentals are calculated. Both the partition function and infrared spectra are shown to be in excellent agreement with those in the experimental HITRAN database, with the exception of one band, which we believe is partially mis-assigned in HITRAN.