Rovibrational spectroscopic constants and anharmonic force fields of CH3AsH2 and CH2AsH3: An ab inito study

Abstract The spectroscopic constants and anharmonic force fields of Methylarsine and its isomer are systematically studied by B3LYP, CAM-B3LYP, M06-2X methods utilizing the cc-PVTZ and cc-PVQZ basis sets. The calculated equilibrium geometries, fundamental frequencies, and nuclear quadrupole coupling constants, et al of CH3AsH2 are supported by experimental or theoretical data. The harmonic frequencies, anharmonic constants, et al of CH3AsH2 are predicted for the first time. The anharmonic force fields and spectroscopic constants of CH2AsH3 are also investigated with the same theoretical level. The IR spectra of CH3AsH2 and CH2AsH3 are predicted theoretically, and the red-shifts are found in their peaks.