Calculation of zero field splitting parameters for trimethylenemethane

Abstract
The spin dipole–dipole contribution to the zero field splitting of the 3 A′2ground state of trimethylenemethane has been computed with a b i n i t i o CI wave functions which included selected single and double excitations from the Hartree–Fock configuration. The resulting value of D is 0.020 cm−1. Isotropic and anisotropicproton hyperfine coupling constants were also computed. The difficulty of quantitatively reproducing experimental values for these properties is discussed.