LAUSR

We present a systematic assessment of the density functional tight binding (DFTB) method for calculating heats of formation of fullerenes with isodesmic‐type reaction schemes. We show that DFTB3‐D/3ob can accurately predict ΔfH values of the 1812 structural isomers of C60, reproduce subtle trends in ΔfH values for 24 isolated pentagon rule (IPR) isomers of C84, and predict ΔfH values of giant fullerenes that are in effectively exact agreement with benchmark DSD‐PBEP86/def2‐QZVPP calculations. For fullerenes up to C320, DFTB ΔfH values are within 1.0 kJ mol−1 of DSD‐PBEP86/def2‐QZVPP values per carbon atom, and on a per carbon atom basis DFTB3‐D/3ob yields exactly the same numerical trend of (ΔfH [per carbon] = 722n−0.72 + 5.2 kJ mol−1). DFTB3‐D/3ob is therefore an accurate replacement for high‐level DHDFT and composite thermochemical methods in predicting of thermochemical stabilities of giant fullerenes and analogous nanocarbon architectures.