Development of the Hamiltonian and matrix elements for partially deuterated methoxy radical

Abstract

The effects of partial deuteration of the methoxy radical upon the ground state Hamiltonian are considered. Methoxy exhibits Jahn–Teller distortion and has an unpaired electron somewhat complicating the situation. Two approaches are considered. One, named the internal axis treatment, sets up the rotational and spin–rotation Hamiltonians with the axis of quantization aligned along the direction of the orbital angular momentum. The other, named the principal axis treatment, chooses the axis of quantization along the a-axis. The internal axis method is preferred because the perturbation Hamiltonian needed to treat CH₃O is simply expressed and has simple matrix elements with this choice.