Correlation data for two NMR computational methods (all using B3LYP/6-31+G(d,p) geometries): Left: B3LYP/6-31G Middle: B3LYP/6-31+G(d,p); Right: B3LYP/6-311+G(2d,p). Mono-cyclic aromatic compounds (group A, Chart 1) are shown in green, non-heterocyclic compounds (group B) are shown in grey, and bicyclic-heterocyclic compounds (group C) are shown in yellow.