Table 6:

Deviations from additivity, ($\Delta E_{\text{add}}^{\text{ZPVE}}-\Delta E^{\text{ZPVE}}$), for scaled harmonic ZPVE^a,b

compound	($\Delta E_{\text{add}}^{\text{ZPVE}}-\Delta E^{\text{ZPVE}}$)/kJ·mol−1
	I	II	III	IV	V	VI	VII
methane	0.0	0.1	0.2	−0.1	−0.3	−0.3	0.4
ethane	−0.1	−0.1	− 0.1	0.0	0.1	−0.1	0.0
propane	0.3	0.0	0.1	0.3	0.6	0.4	0.1
ethylene	0.2	0.1	0.2	0.1	−0.1	−0.2	−0.4
ethyne	0.7	1.0	1.0	0.2	0.2	0.4	−1.0
benzene	−0.2	−0.2	−0.1	−0.3	−0.3	0.0	0.4
H2	0.2	0.1	0.1	0.4	0.2	0.1	−0.2
water	−0.3	0.1	0.1	−0.3	−0.2	0.2	−0.2
carbon dioxide	0.2	0.1	0.2	0.2	0.2	0.0	0.2
methanal	−0.1	0.0	0.0	0.0	−0.1	−0.1	−0.2
furan	−0.3	−0.4	−0.6	−0.2	−0.1	−0.2	−0.2
N2	0.0	−0.2	−0.2	0.0	−0.1	−0.2	−0.2
ammonia	−0.4	0.0	−0.2	−0.5	−0.5	−0.1	0.1
HCN	−0.1	0.4	0.3	0.4	0.3	0.1	0.3
N2O	0.3	0.1	0.1	0.1	0.2	0.1	0.0
standard deviation	0.3	0.4	0.4	0.3	0.3	0.2	0.4

^atheory level labels (Roman numerals) are defined in Table 4

^bbased on ΔE^ZPVE values from Table 5