Theoretical study of the effects of spin-orbit coupling on the valence photoelectron spectrum of HfCl4

The ground state valence electronic structure and ionisation energies of HfC14 are calculated using quasi-relativistic local density functional theory. The optimised Hf-Cl bond length exactly matches the experimentally determined value. The calculated ionisation energies are ca. 0.5–0.7 eV lower than the experimental, and suggest a reversal of the assignment of bands c and d in the photoelectron spectrum. The 0.14 eV separation of the fine structure of band b is reproduced exactly, and is traced to spin-orbit coupling in the parent t2 molecular orbital. This spin-orbit splitting is due to a metal p atomic orbital contribution to the t2 orbital.