where H is the Hessian of Ẽ(G) at the G minimum. D is here the absolute GEO scale, which by Eq 3 gives us GEO value when the exact geometry is compressed ues are within 1% of CCSD(T) ones and even HF gives reasonable values. Thus, the D values are always computed here at the B3LYP/AVTZ level, and are reported for the B2se molecules in Figure . As said, the main idea of D is to give a scale on which GEO does grow with a molecular size. Thus, we define: