Abstract
The R-matrix method as described by Burke and Taylor (1975) is applied to the photoionisation of neutral calcium from the 1Se ground state. Configuration-interaction wavefunctions are used to describe the initial Ca state and final Ca+ states. Total photoionisation cross sections are calculated for photon energies in the range 6.11 eV (2S threshold of Ca+) to 9.25 eV (2P threshold of Ca+) and are compared with the experimental measurements of Brown et al. (1973) and Connerade et al. (1980). A Cooper minimum is found just below the 2D threshold of Ca+ and its effect on the neighbouring series of Rydberg resonances is illustrated by a rapid change in the line profile indices, or q values, of these resonances as this minimum is crossed. LS coupling is used throughout.