Theoretical Study of the Electronic Spectrum and ESR of the CH₂OH Radical

The structure of the CH 2 OH radical was optimized at the UHF, UB3LYP, and MP2 levels. The calculated ionization potential was very close to the experimental one. The transition dipole moments from the ground state to the first four lowest excited states were calculated with and without C s symmetry using the multireference single and double configuration interaction method (MRSD). The first four lowest excited states were also optimized with the single excitation configuration interaction method (CIS). The adiabatic excitation energies and transition dipole moments for vertical emission were calculated at the same level. None of these calculations lead to the assignment of the first excited Rydberg p state as 2 A ‘ ‘(3 p z ) as suggested in a recent paper ( Chem. Phys. Lett. 318, 393, 2000 ). Some results of multireference perturbation theory are also presented. The isotropic hyperfine parameters calculated with MRSD were in good agreement with the experimental values.