Table 1. Summary of Favorable Interaction Types, Interaction Partners, and Geometry Definitions^a.

interaction type	interacting atom types	cutoff distance, dcut [Å]	angle definitions
hydrogen bond	hdon | hacc	0.2	sp: 135.0 ≤ (hdon···hacc–X) ≤ 180.0b
			sp2: 80.0 ≤ (hdon···hacc–X) ≤ 180.0b and
			30.0 ≤ () ≤ 90.0b
			sp3: 70.0 ≤ (hdon···hacc–X) ≤ 180.0b
metal	met | hacc	0.2	see hydrogen bond, with hdon replaced by met
ionic	cat | ani	1.0
cation–dipole	cat | dneg	0.7	120.0 ≤ (cat···dneg–X) ≤ 180.0
cation-π	cat | π	0.5	0.0 ≤ () ≤ 45.0
dipolar	dpos | dneg	0.4	60.0 ≤ (dneg1···dpos2–dneg2) ≤ 120.0 or
			150.0 ≤ (dneg1···dpos2–dneg2) ≤ 180.0b
halogen bond	σpos | σneg	0.2	120.0 ≤ (σneg···σpos–X) ≤ 180.0
			80.0 ≤ (σpos···σneg–X) ≤ 180.0
hydrogen bond donor−π	hdon | π	0.2	0.0 ≤ () ≤ 45.0
			see also hydrogen bond, with hacc replaced by πcen
π–π	π | π	0.5	() ∈ [0.0–35.0; 55.0–125.0; 145.0–180.0]
			parallel: distance (π1···π2cen) ≥ 2.0 Å and distance (π2···π1cen) ≥ 2.0 Å
			orthogonal: distance (π1···π2cen) ≥ 2.0 Å or distance (π2···π1cen) ≥ 2.0 Å
vdW	hyd | hyd	0.5

^aAn interaction between two atoms A and B is counted as favorable if (a) their distance is below r_vdW,A + r_vdW,B + d_cut, where r_vdW are 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. X denotes a covalently attached non-hydrogen atom and n⃗ stands for the normal vector of the plane. For hydrogen bonds and metal interactions, angle definitions are dependent on the hybridization states of donor and acceptor, respectively.

^bAnalogous terms with exchanged atom types are additionally used.