Quintet States 1s2s2p2 5P and 1s2p3 5So for Be-Like Systems

By systematic Rayleigh–Ritz variation calculations, the energies are reported for the core-excited states 1s2s2p2 5P and 1s2p3 5So in the Be-like isoelectronic sequence (Z = 11–20). Energy corrections, including the restricted variational method, mass polarisation, and relativistic effect, are considered to improve the accuracy of energy. The oscillator strengths and transition wavelength between these states are also reported. Computational data on hyperfine structures presented in this paper are calculated for the first time.