Table 6.

23 Proton Affinities with Acidic Oxygen in kcal/mol: Deviation of DFTB in Comparison to G3B3^a

	G3B3	DFTB2		DFTB3
		γ	γ h	γ	diag		full
parameter setb				calc	calc	fit	calc	fit
H2O	398.4	+16.3	+18.5	+8.0	+5.8	−1.6	+7.5	−1.8
2H2O	375.9	+9.6	+5.7	+8.0	+2.3	−3.2	+1.7	−5.1
3H2O	365.0	+8.1	+1.9	+7.7	−0.4	−5.6	−0.7	−7.1
4H2O	359.1	+7.0	+0.3	+7.5	−0.1	−5.2	−0.5	−6.5
5H2O	348.4	+9.2	−1.1	+9.6	−3.7	−8.7	−1.6	−8.3
CH3OH	392.6	−5.7	−2.6	+3.3	+5.8	−0.7	+5.9	−0.3
CH3CH2OH	388.3	−1.5	+1.6	+6.5	+9.3	+2.6	+9.0	+2.2
CH3CH2CH2OH	387.6	−2.2	+1.0	+6.0	+8.7	+1.9	+8.6	+2.0
CH3-CH(OH)-CH3	385.6	+1.4	+4.7	+8.2	+11.7	+4.6	+10.7	+3.3
HCOOH	351.2	+1.7	+3.4	+8.6	+14.2	+7.1	+10.0	+2.9
CH3COOH	355.1	+1.1	+3.2	+6.8	+12.7	+5.6	+8.5	+0.6
CH3CH2COOH	354.5	+1.0	+3.4	+7.5	+13.1	+6.0	+9.3	+1.5
C6H5OH	356.7	−4.7	−2.4	+8.0	+11.0	+5.2	+9.7	+4.0
p-CH3-C6H4OH	357.9	−5.6	−3.1	+7.4	+10.5	+4.5	+9.2	+3.7
p-NO2-C6H4OH	334.6	−9.3	−7.5	+2.2	+5.2	−0.7	+3.5	−1.3
H3O+	171.2	−0.4	−4.7	+10.6	+9.0	+5.6	+6.3	+4.3
2H2O(H+)	200.2	−3.3	−2.7	+6.3	+6.6	+2.3	+5.4	+2.2
3H2O(H+)	213.4	−5.3	−5.1	+4.4	+3.2	−0.9	+2.3	−1.2
4H2O(H+)	221.1	−4.7	−5.3	+4.9	+3.3	−0.7	+2.0	−1.4
5H2O(H+)	226.7	−5.3	−5.1	+3.5	+3.8	−0.4	+1.4	−1.9
CH3OH+2	186.8	−8.3	−10.3	+6.5	+6.1	+2.0	+4.6	+2.2
H2COH+	177.1	−11.8	−13.8	+4.3	+4.3	+0.5	+2.6	−0.2
CH3CHOH+	190.2	−10.1	−10.8	+5.8	+6.5	+2.4	+5.1	+2.0
MUE		5.8	5.1	6.6	6.8	3.4	5.5	2.9
MSE		−1.0	−1.3	+6.6	+6.5	+1.0	+5.2	−0.2
MAX		16.3	18.5	16.6	14.2	8.7	10.7	8.3

^aThe molecules are given in the protonated form. The proton affinity is computed with the potential energies at 0 K without any zero-point energy correction. For the DFTB methods the deviation is given as the difference to the G3B3 method (E^method – E^G3B3). The compilation of the molecules is taken from ref 39.

^bexplanations see Table 1 and Table 2