Anharmonic force fields and spectroscopic constants of H 2 AsO: An ab initio study

Abstract

The anharmonic force fields and spectroscopic constants of the electronic ground state ( ${\tilde{\mathrm{X}}}^1{\mathrm{A}}^{\prime }$ ) for H₂AsO are calculated employing DFT (B3LYP, B3PW91, and B3P86) and MP2 methods with the aug-cc-pVQZ and aug-cc-pV5Z basis sets. The calculated equilibrium geometries, ground state rotational constants, harmonic frequencies, and anharmonic constants of H₂AsO are in comparison with the experimental or previous theoretical data. The best agreement is found at the B3PW91/aug-cc-pV5Z theoretical level. The theoretically predicted fundamental vibrational frequencies, vibration–rotation interaction constants, equilibrium quartic and sextic centrifugal distortion constants, Coriolis coupling constants, cubic and quartic force constants of H₂AsO are obtained at the B3PW91/aug-cc-pV5Z level and expected to provide help for the observation of the high-resolution rotational spectrum of H₂AsO in the future.