Relativistic ab initio model potential calculations including spin–orbit effects through the Wood–Boring Hamiltonian

Presented in this paper, is a practical implementation of the use of the Wood–Boring Hamiltonian [Phys. Rev. B 18, 2701 (1978)] in atomic and molecular ab initio core model potential calculations (AIMP), as a means to include spin–orbit relativistic effects, in addition to the mass-velocity and Darwin operators, which were already included in the spin-free version of the relativistic AIMP method. Calculations on the neutral and singly ionized atoms of the halogen elements and sixth-row p-elements Tl–Rn are presented, as well as on the one or two lowest lying states of the diatomic molecules HX, HX+, (X=F, Cl, Br, I, At) TlH, PbH, BiH, and PoH. The calculated spin–orbit splittings and bonding properties show a stable, good quality, of the size of what can be expected from an effective potential method.