Prospects for an electron electric-dipole moment search in metastable ThO and Th F+

The observation of an electron electric-dipole moment (EEDM) would have major ramifications for the standard model of physics. Polar molecules offer a near-ideal laboratory for such searches due to the large effective electric field (Feff), on order of tens of GV/cm that can be easily oriented in the laboratory frame. We present an improved method for simply and accurately determining Feff, in a heavy polar molecule, allowing for a quick determination of candidates for an EEDM experiment. We apply this method to ThO and Th F+, both of which possess metastable Δ3 electronic states. The values of Feff in ThO and Th F+ are estimated to be 104 GV cm and 90 GV cm, respectively, making them two of the best known candidates for the EEDM search.