Relativistic modifications of covalent bonding in heavy elements: The Kappa valence method

It is shown by using the relativistic generalization of spin-valence theory that the j-j coupled ground state of an element having a single valence electron in a Dirac-Fock anti p or p orbital can form a stable covalent bond to a hydrogen atom. The bond is shown to be a mixture of a normal covalent sigma bond and the triplet bond formed by the interaction of two electrons occupying orthogonal orbitals. (orig.)