Relativistic R-matrix calculations for the photoionization of W63+ ions

The direct and resonant single-photon photoionization of W63+ ions from their ground state 1s22s22p63s 2S1/2 as well as from four lowly excited states 1s22s22p63p 2P1/2,3/2 and 1s22s22p63d 2D3/2,5/2 has been investigated within the framework of the multiconfigurational Dirac-Fock method and the relativistic R-matrix method. Special attention has been paid to exploring direct and resonant ionization limits and to identifying possible resonance symmetries of W63+ ions. To this end, the photoionization cross sections are calculated by using the DARC package. For the ground-state photoionization of W63+ ions, the direct and resonant ionization limits are obtained and the identified resonance peaks are found to be associated with the resonances 1s22s22p53lnl' and 1s22s2p63lnl' (l,l'=s, p, d) at a level of fine-structure energy level or configuration. For the excited-state photoionization, however, the resonant ionization limits and resonance peaks are hardly distinguishable due to much more densely spaced resonance peaks and complicated resonance structure, although the respective direct ionization limits are obtained. We expect that the present work could fill the existing vacancy of essential studies on the photoionization of W63+ ions and be helpful to the diagnosis and simulation of fusion plasmas together with available photoionization data for tungsten ions with other charge states.