DFT anharmonic force field,and spectroscopic constants for phosphaethene,CH 2 PH

Abstract

The anharmonic force field and spectroscopy constants for phosphaethene are determined using density functional theory with B3PW91 and B3LYP functions employing cc-pVTZ and cc-pVQZ basis sets, respectively. Molecular structure, dipole moment and rotational spectroscopic constants are compared with obtainable experimental data. Most of the DFT results are close to observations for centrifugal distortion constants both in A-reducted and S-reducted form. The equilibrium states rotational constants computed by B3LYP/cc-pVQZ level of theory are in good agreement with observations, about only 0.07% higher than experimental ones. Vibrational spectroscopy constants and force constants are predicted by B3LYP. Vibrational frequencies, S-reduction quartic centrifugal distortion constants and rotational constants for several isotopomers of phosphaethene (¹³CH₂PH, CD₂PH, CH₂PD, and CD₂PD) are also calculated at the same levels. The isotopic effects of substitution by atom D are stronger than substitution by atom ¹³C for some rotational spectroscopic parameters.