The combined sets of molecules contain 34,241 unique molecules, and out of these it was possible to compute the SQM storage density for 24,388 molecules. The remaining molecules did either not converge, or the connectivity changed during the optimization, and are therefore unlikely to be good candidates. For the remaining 22,258 molecules with storage densities above 0.4 kJ/g, we performed an adiabatic scan with PM3 to rapidly Of the 954 molecules the majority have back reaction barriers that are smaller than the parent molecule. However, we do find one molecule, shown in Table , with a relatively high storage density and barrier height (Figures and). The molecule is subjected to a more thorough DFT investigation, as described in the supporting information, and the resulting reaction enthalpy and Gibbs free activation energy is shown in Table . The best thermal heat battery candidate is therefore 9 with a predicted energy density of 0.38 kJ/g and a barrier height of 130.0 kJ/mol. For comparison the energy density of the parent system (0.14 kJ/g) is almost three times lower, while the barrier height (119.1 kJ/mol) is 11 kJ/mol lower. According to TS theory, an 11 kJ/mol increase in barrier height increases the half life by a factor of 85, i.e. from 3-39 hours (depending on solvent) to about 10 days -4 months. The computed absorption spectrum of 9 is shown in Figure , together with that of the parent system. Compound 9 retains an absorption peak abound 350 nm, but the intensity is reduced by about a factor of three.