To investigate how well the static binding approximation holds, we tested it on the Thiel's set of small organic molecules (Figure ), for which the ZPR was investigated in ref 11. We computed ΔEgap using orbital derivatives and compared it to ΔES1 obtained using TD-DFT (B3LYP 18 /def2-SVP), calculated for geometries modulated along each normal mode Qi by the standard deviation of the thermal distribution σi(T):