Table 2. Optimized values of the pre-exponential repulsion parameters, A (in kJ mol⁻¹), for all hydrogen-bond acceptor/donor combinations in the four newly parameterized potentials.

The original W99 values are given for reference. These parameters are supplied in eV in the supporting information.

Acceptor atom	W99	W99rev631†	W99rev6311‡	W99rev631P§	W99rev6311P¶
	Donor atom: H2
O1	9330	9745	12 447	12 157	14 859
O2	10 141	7429	10 131	10 999	12 640
N1	5895	12 640	14 376	15 631	18 043
N2	6079	11 964	16 017	13 315	14 473
N3	8327	11 096	15 727	12 736	13 894
N4	12 099	12 099††	12 099††	12 099††	12 099††
	Donor atom: H3
O1	5278	5596	12 254	10 034	13 315
O2	5741	8587	12 833	11 192	12 447
N1	3338	9841	6754	12 833	8877
N2	3445	11 385	11 385	13 701	17 946
N3	4708	4708††	4708††	4708††	4708††
N4	6850	6850††	6850††	6850††	6850††
	Donor atom: H4
O1	13 575	4631	5403	11 385	13 797
O2	14 753	11 192	10 806	14 376	13 508
N1	8587	9263	13 604	13 894	18 525
N2	8848	7719	7429	12 447	14 569
N3	12 119	4149	3280	5596	4921
N4	17 609	18 911	19 104	20 455	19 008

^†The W99rev631 potential is combined with atomic multipoles derived from a B3LYP/6-31G** charge density.

^‡The W99rev6311 potential is combined with atomic multipoles derived from a B3LYP/6-311G** charge density.

^§The W99rev631P potential is combined with atomic multipoles derived from a B3LYP/6-31G** charge density calculated within a polarizable continuum model ().

^¶The W99rev6311P potential is combined with atomic multipoles derived from a B3LYP/6-311G** charge density calculated within a polarizable continuum model ().

^††Interactions that were not re-parameterized retain the original W99 repulsion parameters.