Table summarizes the total reference data in the parameter optimization. The Tor-sionDrive procedure used Q-Chem 4.4 to perform the energy minimizations and the Work Queue library to distribute the independent minimizations at each step of the wavefront propagations. The final MP2 optimizations were carried out using Psi4 1.1 called from the geomeTRIC geometry optimization package; Psi4 was also used for the single-point energy and gradient calculations as well as the vibrational analysis.