Many-body calculations of electric-dipole amplitudes for transitions between low-lying levels of Mg, Ca, and Sr

To support efforts on cooling and trapping of alkaline-earth-metal atoms and designs of atomic clocks, we performed ab initio relativistic many-body calculations of electric-dipole transition amplitudes between low-lying states of Mg, Ca, and Sr. In particular, we report amplitudes for ¹→P₁ᵒ¹S₀,³S₁,¹D₂, for ³→P₁ᵒ¹S₀,¹D₂, and for ³→P₂ᵒ¹D₂ transitions. For Ca, the reduced matrix element 〈4s4p¹P₁ᵒ||D||4s²¹S₀〉 is in good agreement with a high-precision experimental value deduced from photoassociation spectroscopy [Zinner et al., Phys. Rev. Lett. 85, 2292 (2000)]. An estimated uncertainty of the calculated lifetime of the 3s3p¹P₁ᵒ state of Mg is a factor of 3 smaller than that of the most accurate experiment. Calculated binding energies reproduce experimental values within 0.1-0.2%.