Table 4.

The most frequently used features for all 6-feature models^a.

Number	Feature name	Occurrence (50 models)	Meaning
11	AbsCarboxy	36	Indicator for carboxylic acid†
268	ESP-FHASA_Fractional_HASA_(HASA/TMSA)_Quantum-Chemical_PC	14	H-acceptor surface area/total molecular surface area#
101	Topographic_electronic_index_(all_bonds)_Zefirov's_PC	12	Topological electronic index for all bonded pairs of atomsb‡
8	M_PSA_7.4	11	PSA at pH 7.4c§
267	ESP-HASA_H-acceptors_surface_area_Quantum-Chemical_PC	10	H-acceptor surface area#
5	delta_log⁡D	9	log⁡D (pH 6.5) − log⁡D (pH 7.4)d,e∧
7	M_PSA_7.0	9	PSA at pH 7.0§
138	HA_dependent_HDCA-2_[Zefirov's_PC]	9	H-donors charged surface area#
6	M_PSA_6.5	8	PSA at pH 6.5§
1	M_log⁡P	7	log⁡P ∧

^aRows with the same symbol could be categorized into the same group.

^bTopological electronic index is a feature to characterize the distribution of molecular charge: T = ∑_(i<j) ^N_B(|q _i − q _j|/r ² _ij), where q _i is net charge on ith atom and r _ij is the distance between two bonded atoms.

^c7.4 is the pH in blood.

^d6.5 is the pH in intestine.

^e D is the ratio of the sum of the concentrations of all species of a compound in octanol to the sum of the concentrations of all species of the compound in water. For neutral compounds, log⁡D is equal to log⁡P.