Diatomic molecules of alkali-metal and alkaline-earth metal atoms: interaction potentials, dipole moments, and polarizabilities

Ultracold diatomic molecules find application in quantum studies ranging from controlled chemistry and precision measurement physics to quantum many-body simulation and potentially quantum computing. Accurate knowledge of molecular properties is required to guide and explain ongoing experiments.

In an extensive and comparative study, we theoretically investigate the electronic properties of ground-state diatomic molecules composed of alkali-metal (Li, Na, K, Rb, Cs, Fr) and alkaline-earth-metal (Be, Mg, Ca, Sr, Ba, Ra) atoms. We study 78 hetero- and homonuclear diatomic combinations, including 21 alkali-metal molecules in the X¹Σ⁺ and a³Σ⁺ electronic states, 36 alkali-metal–alkaline-earth-metal molecules in the X²Σ⁺ electronic state, and 21 alkaline-earth-metal molecules in the X¹Σ⁺ electronic state. We calculate potential energy curves, permanent electric dipole moments, and polarizabilities using the CCSD(T), CCSDT, and also CCSDTQ coupled cluster methods with large Gaussian basis sets and small-core relativistic-energy-consistent pseudopotentials. We collect and analyze corresponding spectroscopic constants. We review previous experimental and theoretical data and compare them with the present values to establish a new theoretical benchmark. The obtained results should be useful for further application of the studied molecules in modern ultracold physics and chemistry experiments.