Anharmonic force fields and spectroscopic constants of H2AsO: An ab initio study.

The anharmonic force fields and spectroscopic constants of the electronic ground state ( X ˜ 1 A ′ ) 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. [ABSTRACT FROM AUTHOR]