  This paper deals with the electronic structure of RbSr, a molecule possessing
both a permanent magnetic and electric dipole moment in its own frame allowing
its manipulation with external fields. Two complementary ab-initio approaches
are used for the ground and lowest excited states: first, an approach relying
on optimized effective core potentials with core polarization potentials based
on a full configuration interaction involving three valence electrons, and
second, an approach using a small-size effective core potential with 19
correlated electrons in the framework of coupled-cluster theory. We have found
excellent agreement between these two approaches for the ground state
properties including the permanent dipole moment. We have focused on studies of
excited states correlated to the two lowest asymptotes Rb(5p)+Sr(5s) and
Rb(5s)+Sr(5s5p) relevant for ongoing experiments on quantum degenerate gases.
We present also the Hund c) case potential curves obtained using atomic
spin-orbit constants. These potential curves are an excellent starting point
for experimental studies of molecular structure of RbSr using high-resolution
spectroscopy.
