Theoretical study of the spectroscopic constant and anharmonic force field of PO - 2

The equilibrium structure, spectroscopy constants and anharmonic force field of PO − anion have been investigated at MP2, B3LYP, B3P86, B3PW91 methods employing three basis sets, 6-311++G(2d,2p),6-311++G(3df,3pd)and cc-pVQZ, respec- tively. The computed geometries, rotational constants, vibration-rotation interaction constants, quartic centrifugal distortion constants, and coriolis coupling constants of PO − 2 are compared with the available experimental or theoretical data. The fundamen- tal frequencies, rotational constants of ground state, sextic centrifugal distortion con- stants, cubic and quartic force constants of PO − 2 arefirstly predicted. The calculated re- sults show that the B3P86/6-311++G(3df, 3pd) results are in excellent agreement with experiment and represent a substantial improvement over the results obtained from MP2. The other DFT methods are also advisable choices to study the anharmonic force field of PO − . The predicted spectroscopic constants may provide the useful data for the experiment studies of the corresponding spectroscopic constants of PO −