Radiative transitions and van der Waals coefficients for francium

Francium has been the least-studied alkali-metal atom until recently. We present accurate calculations for the discrete and continuum optical transitions, and dispersion coefficients for two colliding francium atoms. Spin-orbit coupling is explicitly included and the influence of core polarization on the energies and the electric dipole operator is considered. Predictions for a range of transition amplitudes that are needed for parity violation experiments are made. The van der Waals coefficients for the long-range collision of two-ground-state Fr atoms in different fine-structure levels show a departure from an established trend in other alkali-metal atoms. We comment on the differences.