Comparison of the electronic spin-orbit splitting in CH3O using UHF and RHF wavefunctions

Abstract

The electronic spin-orbit splitting λe of methoxy was calculated using RHF wavefunctions and a semiempirical spin-orbit hamiltonian. The result, λe = -158 cm-1, agrees well with a calculation that used a RHF wavefunction and the relativistic Breit hamiltonian (λe = -142 cm-1). However, this result does not agree with a calculation that used the same semiempirical spin-orbit hamiltonian and an UHF wavefunction (λe = -78 cm-1). The disagreement arises from the form of the UHF and RHF wavefunctions. The experimental evidence is not sufficiently conclusive for one to decide which wavefunction gives a better description of methoxy.