1	nCp		number of terminal primary C(sp3) Y = any terminal atom or heteroaromatic group (i.e. H, X, OH, NH2, etc.)
2	nCs		number of total secondary C(sp3) Y = H or any heteroatom
3	nCt		number of total tertiary C(sp3) Y = H or any heteroatom
4	nCq		number of total quaternary C(sp3)
5	nCrs		number of ring secondary C(sp3) Y = H or any heteroatom
6	nCrt		number of ring tertiary C(sp3) Y = H or any heteroatom
7	nCrq		number of ring quaternary C(sp3)
8	nCar	Sum of all the carbons belonging to any aromatic and heteroaromatic structure	number of aromatic C(sp2)
9	nCbH		number of unsubstituted benzene C(sp2)
10	nCb–		number of substituted benzene C(sp2) Y = carbon or any heteroatom
11	nCconj		number of non-aromatic conjugated C(sp2)
12	nR=Cp		number of terminal primary C(sp2) Y = any terminal atom or heteroaromatic group (i.e. H, X, OH, NH2, etc.)
13	nR=Cs		number of aliphatic secondary C(sp2) Y = H or any heteroatom
14	nR=Ct		number of aliphatic tertiary C(sp2)
15	n=C=		number of allenes groups
16	nR#CH/X		number of terminal C(sp) Y = any terminal atom or heteroaromatic group (i.e. H, X, OH, NH2, etc.)
17	nR#C–		number of non-terminal C(sp) Y = C or any non-terminal heteroatom
18	nROCN		number of cyanates (aliphatic)
19	nArOCN		number of cyanates (aromatic)
20	nRNCO		number of isocyanates (aliphatic)
21	nArNCO		number of isocyanates (aromatic)
22	nRSCN		number of thiocyanates (aliphatic)
23	nArSCN		number of thiocyanates (aromatic)
24	nRNCS		number of isothiocyanates (aliphatic)
25	nArNCS		number of isothiocyanates (aromatic)
26	nRCOOH		number of carboxylic acids (aliphatic)
27	nArCOOH		number of carboxylic acids (aromatic)
28	nRCOOR		number of esters (aliphatic) Y = Ar or Al (not H)                                  Al = H or aliphatic group linked through C
29	nArCOOR		number of esters (aromatic) Y = Al or Ar
30	nRCONH2		number of primary amides (aliphatic) Al = H or aliphatic group linked through C
31	nArCONH2		number of primary amides (aromatic)
32	nRCONHR		number of secondary amides (aliphatic)   Y = Ar or Al (not H, not C = O) Al = H or aliphatic group linked through C
33	nArCONHR		number of secondary amides (aromatic) Y = Ar or Al (not H, not C = O)
34	nRCONR2		number of tertiary amides (aliphatic)   Y = Ar or Al (not H, not C = O) Al = H or aliphatic group linked through C
35	nArCONR2		number of tertiary amides (aromatic) Y = Ar or Al (not H, not C = O)
36	nROCON		number of (thio-) carbamates (aliphatic) Y = O or S Al = H or aliphatic group linked through any atom
37	nArOCON		number of (thio-) carbamates (aromatic) Y1 = O or S Y2 = H or aliphatic or aromatic group linked through any atom Ar = aromatic group linked through any atom
38	nRCOX		number of acyl halogenides (aliphatic)
39	nArCOX		number of acyl halogenides (aromatic)
40	nRCSOH		number of thioacids (aliphatic)
41	nArCSOH		number of thioacids (aromatic)
42	nRCSSH		number of dithioacids (aliphatic)
43	nArCSSH		number of dithioacids (aromatic)
44	nRCOSR		number of thioesters (aliphatic) Y = Ar or Al (not H) Al = H or aliphatic group linked through C
45	nArCOSR		number of thioesters (aromatic)
46	nRCSSR		number of dithioesters (aliphatic) Y = Ar or Al (not H) Al = H or aliphatic group linked through C
47	nArCSSR		number of dithioesters (aromatic) Y = Ar or Al (not H)
48	nRCHO		number of aldehydes (aliphatic)
49	nArCHO		number of aldehydes (aromatic)
50	nRCO		number of ketones (aliphatic)
51	nArCO		number of ketones (aromatic) Y = Al or Ar
52	nCONN		number of urea (-thio) derivatives Y = O or S
53	nC=O(OR)2		number of carbonate (-thio) derivatives Y = O or S
54	nN=C-N<		number of amidine derivatives Y = C or H
55	nC(=N)N2		number of guanidine derivatives
56	nRC=N		number of imines (aliphatic)  Y = H,C or N (two-connected) Al = H or aliphatic group linked through C
57	nArC=N		number of imines (aromatic) Y = H,C or N (two-connected)
58	nRCNO		number of oximes (aliphatic) Y = H, Ar or Al
59	nArCNO		number of oximes (aromatic) Y = H, Ar or Al
60	nRNH2		number of primary amines (aliphatic) Al = aliphatic group linked through C  (not C = O)
61	nArNH2		number of primary amines (aromatic)
62	nRNHR		number of secondary amines (aliphatic) Al = aliphatic group linked through C  (not C = O)
63	nArNHR		number of secondary amines (aromatic) Y = Ar or Al (not C = O)
64	nRNR2		number of tertiary amines (aliphatic) Al = aliphatic group linked through C  (not C = O)
65	nArNR2		number of tertiary amines (aromatic) Y = Ar or Al (not C = O)
66	nN-N		number of N hydrazines Y = C or H
67	nN=N		number of N azo-derivatives Y = C or H
68	nRCN		number of nitriles (aliphatic)
69	nArCN		number of nitriles (aromatic)
70	nN+		number of positive charged N
71	nNq		number of quaternary N
72	nRNHO		number of hydroxylamines (aliphatic) Y = H, Al or Ar
73	nArNHO		number of hydroxylamines (aromatic) Y = H, Al or Ar
74	nRNNOx		number of N-nitroso groups (aliphatic) Al = H or aliphatic group linked through C
75	nArNNOx		number of N-nitroso groups (aromatic) Y = H, Al or Ar
76	nRNO		number of nitroso groups (aliphatic)
77	nArNO		number of nitroso groups (aromatic)
78	nRNO2		number of nitro groups (aliphatic) Al = H or aliphatic group linked through carbon
79	nArNO2		number of nitro groups (aromatic) Al = aromatic group linked through carbon
80	nN(CO)2		number of imides (thio-) Y = H or C                 Y1 = O or S
81	nC=N-N<		number of hydrazones Y = C or H
82	nROH		number of hydroxyl groups Al = aliphatic group linked through any atom
83	nArOH		number of aromatic hydroxyls Ar = aromatic group linked through any atom
84	nOHp		number of primary alcohols
85	nOHs		number of secondary alcohols
86	nOHt		number of tertiary alcohols
87	nROR		number of ethers (aliphatic) Al = aliphatic group linked through C (not C = O, not C # N)
88	nArOR		number of ethers (aromatic) Y = Ar or Al (not C = O, not C # N)
89	nROX		number of hypohalogenides (aliphatic)
90	nArOX		number of hypohalogenides (aromatic)
91	nO(C=O)2		number of anhydrides (thio-) Y = O or S
92	nH2O		number of water molecules
93	nSH		number of thiols
94	nC=S		number of thioketones
95	nRSR		number of sulfides
96	nRSSR		number of disulfides
97	nSO		number of sulfoxides
98	nS(=O)2		number of sulfones
99	nSOH		number of sulfenic (thio-) acids Y = O or S
100	nSOOH		number of sulfinic (thio-/dithio-)acids Y = O or S
101	nSO2OH		number of sulfonic (thio-/dithio-) acids Y = O or S
102	nSO3OH		number of sulfuric (thio-/dithio-) acids Y = O or S
103	nSO2		number of sulfites (thio-/ dithio-) Y = O or S
104	nSO3		number of sulfonates (thio- / dithio-) Y = O or S
105	nSO4		number of sulfates (thio- / dithio-) Y = O or S
106	nSO2N		number of sulfonamides / sulfinamides / sulfenamides (thio- / dithio-)
107	nPO3		number of phosphites / thiophosphites Y = O or S
108	nPO4		number of phosphates / thiophosphates Y = O or S
109	nPR3		number of phosphanes Y = H, C, halogens
110	nP(=O)O2R		number of phosphonates / thiophosphonates Y = O or S Y1 = H, C, halogens
111	nP(=O)R3/nPR5		number of phosphoranes / thiophosphoranes Y = O or S
112	nCH2RX		number of CH2RX
113	nCHR2X		number of CHR2X
114	nCR3X		number of CR3X
115	nR=CHX		number of R=CHX
116	nR=CRX		number of R=CRX
117	nR#CX		number of R#CX
118	nCHRX2		number of CHRX2
119	nCR2X2		number of CR2X2
120	nR=CX2		number of R=CX2
121	nCRX3		number of CRX3
122	nArX		number of X on aromatic ring
123	nCXr		number of X on ring C(sp3)
124	nCXr=		number of X on ring C(sp2)
125	nCconjX		number of X on exo-conjugated C
126	nAziridines		number of Aziridines
127	nOxiranes		number of Oxiranes
128	nThiranes		number of Thiranes
129	nAzetidines		number of Azetidines
130	nOxetanes		number of Oxetanes
131	nThioethanes		number of Thioethanes
132	nBeta-Lactams		number of Beta-Lactams
133	nPyrrolidines		number of Pyrrolidines
134	nOxolanes		number of Oxolanes
135	nth-Thiophenes		number of tetrahydro-Thiophenes
136	nPyrroles		number of Pyrroles
137	nPyrazoles		number of Pyrazoles
138	nImidazoles		number of Imidazoles
139	nFuranes		number of Furanes
140	nThiophenes		number of Thiophenes
141	nOxazoles		number of Oxazoles
142	nIsoxazoles		number of Isoxazoles
143	nThiazoles		number of Thiazoles
144	nIsothiazoles		number of Isothiazoles
145	nTriazoles		number of Triazoles
146	nPyridines		number of Pyridines
147	nPyridazines		number of Pyridazines
148	nPyrimidines		number of Pyrimidines
149	nPyrazines		number of Pyrazines
150	n135-Triazines		number of 135-Triazines
151	n124-Triazines		number of 124-Triazines
152	nHDon	Sum of the hydrogens linked to all of the Os and Ns in the molecule	number of donor atoms for H-bonds (N and O)
153	nHAcc	Total number of Ns, Os and Fs in the molecule, excluding N with a formal positive charge, higher oxidation states and pyrrolyl form of N	number of acceptor atoms for H-bonds (N, O, F)
154	nHBonds		number of intramolecular H-bonds Y1 = B, N, O, Al, P, S Y2 = N, O, F The geometric distance between H and Y2 must be in the range 1 - 2,7 A.

 

 

R: any group linked through carbon; Al: aliphatic chain linked through carbon unless otherwise stated; Ar: aromatic ring linked through carbon unless otherwise stated; X: halogen. The main atom in the functional groups is in red colour, the other atoms defining the group are in black bold face letters. Note that to calculate nHBonds the geometrical descriptors block must be selected along with the functional groups.