INTERPRETATION OF THE HYPERFINE COUPLING-CONSTANTS OF THE BORON TRIMER IN RARE-GAS MATRICES

By carrying out a systematic basis set and electron correlation investigation, we have determined accurately the isotropic and anisotropic parts of the hyperfine coupling tensor of the B3 molecule using the multiconfiguration self-consistent-field restricted-unrestricted method. The anisotropy of the computed tensor is significantly larger than the experimental uncertainty. This indicates that the B3 molecules must be freely tumbling in neon, argon, and krypton matrices at 4 K. The spin polarization of the Is orbital on each B atom is found to be very small in the B3 Molecule. This implies that the isotropic hyperfine coupling is dominated by valence-orbital contributions rather than by 1s-orbital contributions.