Ab initio potential energy surface and rovibrational energies of H2F+

Abstract

A potential energy surface is obtained through ab initio calculations for the H2F+ ion. 8 864 points are calculated within 20000cm−1 from the equilibrium configuration and fitted to the analytical expression used by Partridge and Schwenke in the case of the water molecule [J. Chem. Phys. 106 (1997) 4618–4639]. The ab initio points are reproduced with a root mean square deviation of 4.1cm−1 using 48 parameters. Vibrational energies are calculated with a three dimensional approach yielding more accurate fundamental frequencies for the ν2 and ν3 modes than previous calculations. The potential energy surface is adjusted to high-resolution experimental data varying seven parameters including the bond length and bond angle equilibrium values. The adjusted surface allows us to reproduce the available high-resolution experimental data with a root mean square deviation of 0.014cm−1 up to J=4. Vibrational energies are calculated up to 10000cm−1 and a line list is built up to J=5 for transitions involving the eight first vibrational states.