  Heteronuclear dimers are of significant interest to experiments seeking to
exploit ultracold polar molecules in a number of novel ways including precision
measurement, quantum computing, and quantum simulation. We calculate highly
accurate Born-Oppenheimer total energies and electric dipole moments as a
function of internuclear separation for two such dimers, LiSr and KRb. We apply
fully-correlated, high-accuracy quantum Monte Carlo methods for evaluating
these molecular properties in a many-body framework. We use small-core
effective potentials combined with multi-reference Slater-Jastrow trial wave
functions to provide accurate nodes for the fixed-node diffusion Monte Carlo
method. For reference and comparison, we calculate the same properties with
Hartree-Fock and with restricted Configuration Interaction methods, and
carefully assess the impact of the recovered many-body correlations on the
calculated quantities. For LiSr we find a highly nonlinear dipole moment curve,
which may make this molecule's dipole moment tunable through vibrational state
control.
