Studies on spectroscopic constants for H₂PO and D₂PO free radicals

This work presents a systematic theoretical study on the calculation of the spectroscopic constants of H2PO and D2PO free radicals, computed with Density Functional Theory (DFT). Different functionals of B3LYP, CAM-B3LYP, CAM-B3LYP-D3(BJ), B3LYP-D3(BJ), and wB97XD are employed and discussed in details. Our results of CAM-B3LYP/ cc-pVQZ are in nice agreement with the experiment. The remarkable isotope effect is addressed and discussed. The nice results demonstrate that our predicted values of anharmonic constants and vibrational frequencies, centrifugal distortion constants, vibration-rotation interaction constants, and unknown anharmonic force field of H2PO and D2PO free radicals are accurate enough to provide a theoretical support.