Ground-state photoionization cross sections for lithiumlike carbon, nitrogen, and oxygen

Detailed close-coupling calculations are reported for the photoionization of the ²S ground state of CIV, NV, and OVI. The frozen-core approximation is employed and the eigenfunction expansion includes the ground state and the $n=2$ excited states of the residual heliumlike ions CV, NVI, and OVII. Autoionizing resonances lying below the $n=2$ thresholds are taken into account.