Table 2. Summary of Unfavorable Interaction Types, Interaction Partners, and Geometry Definitions^a.

interaction type	interacting atom types	cutoff distance, dcut [Å]	angle definitions
unf_hydrogen bond	hdon | hdon	0.2	sp: 135.0 ≤ (hdon1···hdon2–X) ≤ 180.0 b
	hacc | hacc		sp2: 80.0 ≤ (hdon1···hdon2–X) ≤ 180.0 b and
			30.0 ≤ () ≤ 90.0b
			sp3: 70.0 ≤ (hdon1···hdon2–X) ≤ 180.0 b
unf_metal	met | hdon	0.2	see hydrogen bond, with hdon2 replaced by met
unf_ionic	cat | cat	1.0
unf_dipolar	dneg | dneg	0.4	60.0 ≤ (dneg1···dneg2–dpos2) ≤ 120.0 or 150.0 ≤ (dneg1···dneg2–dpos2) ≤ 180.0 b
	dpos | dpos
	dneg | ani
clash_apolar (interaction type ∈ [π–π, vdW])		−0.45
clash_polar (interaction type ∉ [π–π, vdW])		–0.7
desolv_donor	hdon | hyd	0.0c	see hydrogen bond, with hdon2 replaced by hyd
		0.8d
desolv_acceptor	hacc | hyd	0.0c	see hydrogen bond, with hdon2 replaced by hyd and hdon1 replaced by hacc
		0.8d

^aAn interaction between two atoms A and B is counted as unfavorable if (a) their distance is below r_vdW,A + r_vdW,B + d_cut, where r_vdW is the van der Waals radii according to Bondi(34) and d_cut is an interaction type-specific distance cutoff, and (b) all involved angular thresholds are fulfilled. For hydrogen bonds, metal interactions, and donor and acceptor desolvation pairs, angle definitions are dependent on the hybridization states of donor and acceptor, respectively.

^bAnalogous terms with exchanged atom types are additionally used.

^cCutoff distance if h_don or h_acc already form a hydrogen bond with h_acc or h_don, respectively.

^dCutoff distance if h_don or h_acc is not already involved in a hydrogen bond and is not solvent-exposed.