Excitation energies, hyperfine constants, E1 transition rates and lifetimes of 4s2nl states in neutral gallium

Abstract

Energies of the 4s2npj (n = 4–8), 4s2ns1/2 (n = 5–8), 4s2ndj (n = 4–7), 4s2nfj (n = 4–5) and 4s25gj states in neutral gallium are obtained using a relativistic many-body perturbation theory (RMBPT) method. First-, second-, third- and all-order Coulomb energies and first-order Breit and second-order Coulomb–Breit corrections are calculated. Reduced matrix elements, oscillator strengths, transition rates and lifetimes are determined for the 130 possible electric-dipole transitions. Hyperfine constants A are determined for 28 4s2nlj states in 69Ga I and 71Ga I isotopes. All above-mentioned properties are obtained in the relativistic single–double (SD) approximation, where single and double excitations of Dirac–Fock wavefunctions are included to all orders of perturbation theory. Using SD wavefunctions, accurate values are obtained for energies of the lowest states and for the possible electric-dipole matrix elements between these states. With the aid of the SD wavefunctions, we also determine transition rates, oscillator strengths and lifetimes. These calculations provide a theoretical benchmark for comparison with experiment and theory.