A small-core multiconfiguration Dirac-Hartree-Fock-adjusted pseudopotential for Tl-application to TlX (X = F, Cl, Br, I)

A relativistic pseudopotential of the energy-consistent variety simulating the Tl21+ (1s - 4f) core has been generated by adjustment to multiconfigura tion Dirac-Hartree-Fock data based on the Dirac-Coulomb-Breit Hamiltonian. Valence ab initio calculations using this pseudopotential have been perform ed for atomic excitation energies and for spectroscopic constants of the X0 (+) and A0(+) states of TlX (X = F, Cl, Br, I). Comparison is made to exper iment and to four-component density functional results.