Forbidden lines in 6p(k) (k=1-5) configurations

Energy levels and radiative transition probabilities have been calculated for states within the 6p(k) (k = 1-5) configurations in the thallium, lead bismuth, polonium and actinium sequences up to radon. Magnetic dipole (M1) and electric quadrupole (E2) transition probabilities have been obtained using average energies, electrostatic and spin-orbit integrals adjusted so as to fit the observed energy levels or, in the absence of experimental data, in an ab initio way. The most important configuration interaction and relativistic effects were included in the calculations, using the relativistic Hartree-Fock method. The validity of the method is assessed through limited comparisons with multiconfiguration relativistic random-phase and multiconfiguration Dirac-Fock results available or calculated along the lead sequence. For many of the forbidden lines considered in the present work, transition probabilities are reported for the first time.