  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. Here, in an
extensive and comparative study, we theoretically investigate the electronic
properties of the 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 $X^1\Sigma^+$ and $a^3\Sigma^+$ electronic
states, 36 alkali-metal--alkaline-earth-metal molecules in the $X^2\Sigma^+$
electronic state, and 21 alkaline-earth-metal molecules in the $X^1\Sigma^+$
electronic state. We calculate potential energy curves, permanent electric
dipole moments, and polarizabilities using the hierarchy of coupled cluster
methods upto CCSDTQ with large Gaussian basis sets and small-core relativistic
energy-consistent pseudopotentials. We collect and analyze corresponding
spectroscopic constants. We estimate computational uncertainties and compare
the present values with previous experimental and theoretical data to establish
a new theoretical benchmark. The presented results should be useful for further
application of the studied molecules in modern ultracold physics and chemistry
experiments.
