ΔHf,298 (kcal/mol)   Molecule Experimental Ab initio-GE Group Additivity Benzene (C6H6) 19.81 20.8 19.8 Pyrene (C16H10) 51.59 51.3 55.1 Coronene (C24H12)   61.5 77.1 Circumcoronene (C54H18)   126 152 2-Circumcoronene (C96H24)   212 244 3-Circumcoronene (C150H30)   320 354

Table 1A: Enthalpy of Formation of Benzene and Highly Fused Aromatics [8].