Electric-dipole, electric-quadrupole, magnetic-dipole, and magnetic-quadrupole transitions in the neon isoelectronic sequence

Excitation energies for 2l-3l^′ hole-particle states of Ne-like ions are determined to second order in relativistic many-body perturbation theory (MBPT). Reduced matrix elements, line strengths, and transition rates are calculated for electric-dipole (E1), magnetic-quadrupole (E2), magnetic-dipole (M1), and magnetic-quadrupole (M2) transitions in Ne-like ions with nuclear charges ranging from Z=11 to 100. The calculations start from a 1s²2s²2p⁶ closed-shell Dirac-Fock potential and include second-order Coulomb and Breit-Coulomb interactions. First-order many-body perturbation theory (MBPT) is used to obtain intermediate-coupling coefficients, and second-order MBPT is used to determine the matrix elements. Contributions from negative-energy states are included in the second-order E1, M1, E2, and M2 matrix elements. The resulting transition energies are compared with experimental values and with results from other recent calculations. Trends of E1, E2, M1, and M2 transition rates as functions of nuclear charge Z are shown graphically for all transitions to the ground state.