Ab initio study of spectroscopic constants and anharmonic force field of FCO2 radical

The equilibrium structure, spectroscopy constants and anharmonic force field of FCO2 have been calculated at DFT and CCSD(T) levels of theory employing two basis sets cc-pVDZ and cc-pVTZ, respectively. The computed equilibrium geometries, rotational constants, fundamental vibrational wave numbers and quartic centrifugal distortion constants are compared with the available experimental data or the previous theoretical values. We also predict the harmonic frequencies, five sextic centrifugal distortion constants, vibration-rotation interaction constants, anharmonic constants, coriolis coupling constants, and cubic and quartic force constants. The calculated results show that the CCSD(T) method is superior to DFT at the calculations of geometries of FCO2, however, for the spectroscopic constants and force constants that B3PW91/cc-pVTZ results are more reliable. Our predictions may provide useful data for the experiment studies of the corresponding spectroscopic constants of FCO2.