© OLGEN exit by Joachim Braun and Christoph Rücker
 
 

The molecular descriptors computed with MOLGEN

General references:

·    TodCon : Todeschini, R.; Consonni, V. Handbook of Molecular Descriptors, Wiley-VCH, Weinheim and New York, 2000

·    Trin: Trinajstić, N. Chemical Graph Theory, 2nd edition, CRC Press, Boca Raton, FL, 1992

0 number of atoms

A, A (incl. H) and N_H are descriptors of the category 'arithmetic'.

Notation in text: ,  and

 is the number of atoms excluding H atoms.  is the number of atoms including H atoms.  is the number of H atoms.

1 number of atoms incl. H atoms

A (incl. H) see 0.

2 number of H atoms

N_H see 0.

3 relative number of H atoms

rel. N_H, rel. N_C, rel. N_O, rel. N_N, rel. N_S,  rel. N_F, rel. N_Cl, rel. N_Br, rel. N_I and rel. N_P are descriptors of the category 'arithmetic'.

Notation in text: , , , , , , , ,  and

Relative means divided by the number of atoms (inclusive H atoms):

Correspondingly , , , , , , , ,  and .

For  see 2, for  see 1.

4 number of C atoms

N_C, N_O, N_N, N_S, N_F, N_Cl, N_Br, N_I and N_P  are descriptors of the category 'arithmetic'.

Notation in text: , , , , , , ,  and

 is the number of C atoms in a molecule.

Correspondingly , , , , , ,  and .

5 relative number of C atoms

rel. N_C see 3.

6 number of O atoms

N_O see 4.

7 relative number of O atoms

rel. N_O see 3.

8 number of N atoms

N_N see 4.

9 relative number of N atoms

rel. N_N see 3.

10 number of S atoms

N_S see 4.

11 relative number of S atoms

rel. N_S see 3.

12 number of F atoms

N_F see 4.

13 relative number of F atoms

rel. N_F see 3.

14 number of Cl atoms

N_Cl see 4.

15 relative number of Cl atoms

rel. N_Cl see 3.

16 number of Br atoms

N_Br see 4.

17 relative number of Br atoms

rel. N_Br see 3.

18 number of I atoms

N_I see 4.

19 relative number of I atoms

rel. N_I see 3.

20 number of P atoms

N_P see 4.

21 relative number of P atoms

rel. N_P see 3.

22 number of bonds

B and B (incl. H)  are descriptors of the category 'arithmetic'.

Notation in text: ,

 is the number of bonds in the H-suppressed molecule.  is the number of  bonds in a molecule containing H atoms.

23 number of bonds (incl. H atoms)

B (incl. H) see 22.

24 number of localized bonding electron pairs

loc. B and loc. B (incl. H) are descriptors of the category 'arithmetic'.

Notation in text:  and

 is the number of localized bonding electron pairs in an H-suppressed molecule. Aromatic π-electrons are delocalized and therefore not counted here.

 is analogous to  but includes bonds to H atoms.

25 number of localized bonding electron pairs (incl. H)

loc. B (incl. H) see 24.

26 number of single bonds

n- and n- (incl. H) are descriptors of the category 'arithmetic'.

Notation in text:  and

 is the number of single bonds in an H-suppressed molecule.  is analogous to  but includes bonds to H atoms.

27 rel. number of single bonds

rel. n- and rel n- (incl. H) are descriptors of the category 'arithmetic'.

Notation in text:  and

rel. n- is relative to the number of bonds of an H-suppressed molecule:

Analogous is:

For  see 26, for  see 22, for  see 28 and for  see 23.

28 number of single bonds (incl. H atoms)

n- (incl. H) see 26.

29 rel. number of single bonds (incl. H atoms)

rel. n- (incl. H) see 27.

30 number of double bonds

n=, n# and n aromatic are descriptors of the category 'arithmetic'.

Notation in text: ,  and

 is the number of double bonds,  the number of triple bonds and  is the number of aromatic bonds.

31 relative number of double bonds

rel. n=, rel. n= (incl. H) , rel. n#, rel. n# (incl. H), rel. n aromatic and rel. n aromatic (incl. H)  are descriptors of the category 'arithmetic'.

Notation in text: , , , ,  and

 is relative to the number of bonds in an H-suppressed molecule.  is relative to the number of bonds in a molecule with H atoms.

Correspondingly , ,  and .

32 relative number of double bonds (incl. H atoms)

rel. n= (incl. H) see 31.

33 number of triple bonds

n# see 30.

34 relative number of triple bonds

rel. n# see 31.

35 relative number of triple bonds (incl. H atoms)

rel. n# (incl. H) see 31.

36 number of aromatic bonds

n aromatic see 30.

37 relative number of aromatic bonds

rel. n aromatic see 31.

38 relative number of aromatic bonds (incl. H atoms)

rel. n aromatic (incl. H) see 31.

39 cyclomatic number

C is a descriptor of the category 'arithmetic'.

Notation in text:

For molecules (connected graphs)  is defined as:

For  see 0, for  see 22.

40 molecular weight

MW and MW (incl. H) are descriptors of the category 'arithmetic'.

Notation in text:  and

 is the sum of the atomic weights in an H-suppressed molecule. The atomic weight is that of the natural abundance isotope mixture.  takes account of the H atoms.

Source:

·    TodCon, page 332

41 mean atomic weight (or average atomic weight)

mean AW and mean AW (incl. H) are descriptors of the category 'arithmetic'.

Notation in text:  and

mean  AW is defined as:

Analogous :

For  and  see 40 and 42. For  and  see 0 and 1.

42 molecular weight (incl. H atoms)

MW (incl. H) see 40.

43 mean atomic weight (incl. H atoms)

mean AW (incl. H) see 41.

44 Wiener index

W is a descriptor of the category 'topological'.

Notation in text:

W is the half-sum of the entries of the distance-matrix of the H-suppressed molecule:

where  is the number of non-H atoms and  is the entry in the ith row and the jth column of the distance matrix.

For  see 0 and for  see distance matrix.

Source:

·    Wiener, H. Structural Determination of Paraffin Boiling Points. J. Am. Chem. Soc. 1947, 69, 17-20

·    TodCon, page 497

45 1st Zagreb index

M_1  is a descriptor of the category 'topological'.

Notation in text:

 is the sum over the squares of the vertex degree of each atom in an H-suppressed molecule:

where  is the number of non-H atoms and  is the number of neighbours of atom i in an H-suppressed molecule.

For  see 0. For  see vertex degree.

Source:

·    Gutman, I.; Ruščić, B.; Trinajstić, N.; Wilcox, C. F. Graph Theory and Molecular Orbitals. XII. Acyclic Polyenes. J. Chem. Phys. 1975, 62, 3399-3405

·    TodCon, page 509

·    Trin, page 226

46 2nd Zagreb index

M_2 is a descriptor of the category 'topological'.

Notation in text:

 is the following sum over all edges:

where  is the number of neighbours of atom i in an H-suppressed molecule.

For  see vertex degree.

Source:

·    Gutman, I.; Ruščić, B.; Trinajstić, N.; Wilcox, C. F. Graph Theory and Molecular Orbitals. XII. Acyclic Polyenes. J. Chem. Phys. 1975, 62, 3399-3405

·    TodCon, page 509

·    Trin, page 226

47 1st modified Zagreb index

m^M_1 and m^M_2 are descriptors of the category 'topological'.

Notation in text:  and

 is the sum over the squares of the reciprocal vertex degree of each atom in an H-suppressed molecule:

 is defined as the following sum over all edges:

 

where  is the number of non-H atoms and  is the number of neighbours of atom i in an H-suppressed molecule.  stands for modified.

For  see 0. For  see vertex degree.

Source:

·    Nikolić, S.; Kovačević, G.; Miličević, A.; Trinajstić, N. The Zagreb Indices 30 Years After. Croat. Chem. Acta, 2003, 76, 113-124

48 2nd modified Zagreb index

m^M_2 see 47.

49 Randic index of order 0 (or connectivity index of order 0)

0^Chi is a descriptor of the category 'topological'.

Notation in text:

This is the zeroth descriptor in the series m^Chi with m = 1, 2, 3, …

Notation in text:

The definition of :

 

where  is the number of non H-atoms and  is the number of neighbours of atom i in an H-suppressed molecule.

For  see 0. For  see vertex degree.

The definition of :

with . The sum runs over all paths of length  (this is the number of edges of the path).  is the number of the atoms in a path . The product runs over all atoms of path .  is the vertex degree of the ith atom in path .

For  see vertex degree.

Source:

·    Randić, M. On Characterization of Molecular Branching. J. Am. Chem. Soc. 1975, 97, 6609-6615

·    Kier, L. B.; Murray, W. J.; Randić, M.; Hall, L. H. Molecular Connectivity V: Connectivity Series Applied to Density. J. Pharm. Sci., 1976, 65, 1226-1230

·    Kier, L. B.; Hall L. H. The Nature of Structure-Activity Relationships and their Relation to Molecular Connectivity. Eur. J. Med. Chem., 1977, 12, 307-312

·    Kier, L. B.; Hall L. H. Molecular Connectivity in Structure-Activity Analysis. Research-Studies Press - Wiley, Chichester (UK), 1986

·    TodCon, pages 84-85

·    Trin, page 226

50 Randic Index of order 1

1^Chi see 49.

51 Randic Index of order 2

2^Chi see 49.

52 solvation connectivity index of order 0

0^Chi^s is a descriptor of the category 'topological'.

Notation in text:

is the zeroth member in the series m^Chi^s with m = 1, 2, 3, …

Notation in text:

The definition of :

where  is the number of non-H atoms and  is the number of neighbours of atom i in an H-suppressed molecule.  is the principal quantum number of atom i (for C, N, O, F: =2; for Si, P, S, Cl: =3).

For  see 0. For  see vertex degree.

The definition of :

with . The sum runs over all paths of length  (this is the number of edges in the path).  is the number of the atoms in a path . The product runs over all atoms in path .  is the vertex degree of the ith atom in path .  is the principal quantum number of atom i in path .

For  see vertex degree.

Source:

·    Zefirov, N. S.; Palyulin, V. A. QSAR for Boiling Points of “Small” Sulfides. Are the “High-Quality Structure-Property-Activity Regressions” the Real High Quality QSAR Models? J. Chem. Inf. Comput. Sci. 2001, 41, 1022-1027

·    TodCon, pages 88-89

53 solvation connectivity index of order 1

1^Chi^s see 52.

54 solvation connectivity index of order 2

2^Chi^s see 52.

55 solvation connectivity index of order 3

3^Chi^s see 52.

56 solvation connectivity index for clusters

3^Chi^s (cluster) is a descriptor of the category 'topological'.

Notation in text:

The definition of  is:

The sum runs over all clusters of size 3:

The product runs over all four atoms of cluster .  is the vertex degree of the ith atom in cluster .  is the principal quantum number of atom i in cluster .

For  see vertex degree.

Source:

·    TodCon, pages 88-89

57 Kier and Hall index of order 0

0^Chi^v is a descriptor of the category 'topological'.

Notation in text:

 is the zeroth member of the series m^Chi with m = 1, 2, 3, …

Notation in text:

The definition of :

 

where  is the number of non-H atoms and  is the valence vertex degree of atom i in an H-suppressed molecule.

For  see 0. For  see valence vertex degree.

The definition of :

 

with . The sum runs over all paths of length  (this is the number of edges of the path).  is the number of atoms in a path . The product runs over all atoms of path .

For  see valence vertex degree.

Source:

·    Kier, L. B.; Murray, W. J.; Randić, M.; Hall, L. H. Molecular Connectivity V: Connectivity Series Applied to Density. J. Pharm. Sci., 1976, 65, 1226-1230

·    Kier, L. B.; Hall L. H. The Nature of Structure-Activity Relationships and Their Relation to Molecular Connectivity. Eur. J. Med. Chem. 1977, 12, 307-312

·    TodCon, pages 85-86

·    Trin, page 229

58 Kier and Hall index of order 1

1^Chi^v see 57.

Source:

·    Kier, L. B.; Hall L. H. Derivation and Significance of Valence Molecular Connectivity. J. Pharm. Sci. 1981, 70, 583-589

·    TodCon, pages 85-86

·    Trin, page 229

59 Kier and Hall index of order 2

2^Chi^v see 57.

60 Kier and Hall index of order 3

3^Chi^v see 57.

61 Kier shape index 1

1^kappa is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of bonds in an H-suppressed molecular graph.

For  see 0. For  see 22.

Source:

·    Kier, L. B. Shape Indexes of Orders One and Three from Molecular Graphs. Quant. Struct.-Act. Relat. 1986, 5, 1-7

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 248-249

62 Kier shape index 2

2^kappa is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of paths of length 2 in an H-suppressed molecular graph.

For  see 0.

Source:

·    Kier, L. B. A Shape Index from Molecular Graphs. Quant. Struct.-Act. Relat. 1985, 4, 109-116

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 248-249

63 Kier shape index 3

3^kappa is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of paths of length 3 in an H-suppressed molecular graph.

For  see 0.

Source:

·    Kier, L. B. Shape Indexes of Orders One and Three from Molecular Graphs. Quant. Struct.-Act. Relat. 1986, 5, 1-7

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 248-249

64 Kier molecular flexibility index non-alpha-modified

Phi_non-alpha is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms. ,  are the Kier shape indices 1 and 2.

For  and  see 61 and 62. For  see 0.

Source:

·    No source! Definition is analogous to 68 without modifying alpha.

65 Kier alpha-modified shape index 1

1^kappa_alpha is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of bonds in an H-suppressed molecular graph.  is derived from the covalent radius of each atom.

For  see alpha. For  see 0. For  see 22.

Source:

·    Kier, L. B. Distinguishing Atom Differences in a Molecular Graph Shape Index. Quant. Struct.-Act. Relat. 1986, 5, 7-12

·    Kier, L. B. Shape Indexes of Orders One and Three from Molecular Graphs. Quant. Struct.-Act. Relat. 1986, 5, 1-7

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 249-250

66 Kier alpha-modified shape index 2

2^kappa_alpha is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of paths of length 2 in an H-suppressed molecular graph.  is derived from the covalent radius of each atom.

For  see alpha. For  see 0.

Source:

·    Kier, L. B. Distinguishing Atom Differences in a Molecular Graph Shape Index. Quant. Struct.-Act. Relat. 1986, 5, 7-12

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 249-250

67 Kier alpha-modified shape index 3

3^kappa_alpha is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms and  is the number of paths of length 3 in an H-suppressed molecular graph.  is derived from the covalent radius of each atom.

For  see alpha. For  see 0.

Source:

·    Kier, L. B. Shape Indexes of Orders One and Three from Molecular Graphs. Quant. Struct.-Act. Relat. 1986, 5, 1-7

·    Kier, L. B. Indexes of Molecular Shape from Chemical Graphs. Acta Pharm. Jugosl. 1986, 36, 171-188

·    TodCon, pages 249-250

68 Kier molecular flexibility index

Phi is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms. ,  are the Kier alpha-modified shape indices 1 and 2.  is derived from the covalent radius of each atom.

For  and  see 65 and 66. For  see 0.

Source:

·    Kier, L. B. An Index of Molecular Flexibility from Kappa Shape Attributes. Quant. Struct.-Act. Relat. 1989, 8, 221-224

·    TodCon, page 178

69 Platt number

F is a descriptor of the category 'topological'.

Notation in text:

where  is the number of neighbours of atom i. The sum runs over all edges in an H-suppressed molecular graph.

Source:

·    Platt, J. R. Influence of Neighbor Bonds on Additive Bond Properties in Paraffins. J. Chem. Phys. 1947, 15, 419-420

·    Platt, J. R. Prediction of Isomeric Differences in Paraffin Properties. J. Phys. Chem. 1952, 56, 328-336

·    TodCon, page 125

·    Trin, page 245

70 Gordon-Scantlebury index

N_GS is a descriptor of the category 'topological'.

Notation in text:

 is the number of path subgraphs of length 2 in an H-suppressed molecular graph.

Source:

·    TodCon, page 125

·    Trin, 245

71 Balaban index

J is a descriptor of the category 'topological'.

Notation in text:

where  is the number of bonds and  is the cyclomatic number.  is the ith vertex distance degree. The sum runs over all edges of an H-suppressed molecular graph.

For   see 22. For  see 39. For  see vertex distance degree.

Source:

·    Balaban, A. T. Highly Discriminating Distance-Based Topological Index. Chem. Phys. Lett. 1982, 89, 399-404

·    Balaban, A. T. Topological Indices Based on Topological Distances in Molecular Graphs. Pure Appl. Chem. 1983, 55, 199-206

·    TodCon, page 21

·    Trin, page 246

72 unsaturated Balaban index

J_unsat is a descriptor of the category 'topological'.

Notation in text:

where  is the number of bonds and  is the cyclomatic number.  is the ith vertex unsaturated distance degree, i.e. the row sum in the unsaturated distance matrix.

For   see 22. For  see 39. For  see vertex unsaturated  distance degree.

Source:

·    Balaban, A. T. Highly Discriminating Distance-Based Topological Index. Chem. Phys. Lett. 1982, 89, 399-404

·    Balaban, A. T.; Filip, P. Computer Program For Topological Index J. MATCH – Commun. Math. Comp. Chem. 1984, 16, 163

73 Schultz molecular topological index

MTI is descriptor of the category 'topological'.

Notation in text:

 is defined for an H-suppressed molecular graph:

where  is the adjacence matrix (here not the descriptor : number of atoms),  is the distance matrix,  the number of atoms,  the second  descriptor ,  is the vertex degree of the ith atom and  is the first Zagreb index. The letter  specifies the transposition of a vector or a matrix:  in a symmetric matrix.

For  see adjacence matrix, for  see distance matrix, for  see 74, for  see vertex degree, for  see 45.

Source:

·    Schultz, H. P. Topological Organic Chemistry. 1. Graph Theory and Topological Indices of Alkanes. J. Chem. Inf. Comput. Sci. 1989, 29, 227-228

·    Schultz, H. P.; Schultz, T. P. Topological Organic Chemistry. 6. Graph Theory and Molecular Topological Indices of Cycloalkanes. J. Chem. Inf. Comput. Sci. 1993, 33, 240-244

·    TodCon, page 381 (The formula given there is incorrect.)

·    Trin, page 257

74 MTI'-index

MTI' is a descriptor of the category 'topological'.

Notation in text:

 is defined for an H-suppressed molecular graph:

where  is the adjacence matrix (here not the descriptor : number of atoms),  is the distance matrix,  the number of atoms,  is the vertex degree of the ith atom,  is the vertex distance degree of the ith atom. The letter  specifies the transposition of a vector or a matrix:  in a symmetric matrix.

For  see adjacency matrix, for  see distance matrix, for  see vertex degree and for  see vertex distance degree.

Source:

·    Müller, W. R.; Szymanski, K.; Knop, J. v.; Trinajstić, N. Molecular Topological Indices. J. Chem. Inf. Comput. Sci. 1990, 30, 160-163

·    Mihalić, Z.; Nikolić, S; Trinajstić, N. Comparative Study of Molecular Descriptors Derived from the Distance Matrix. J. Chem. Inf. Comput. Sci. 1992, 32, 28-37

·    TodCon, page 381

75 Harary number

H is a descriptor of the category 'topological'.

Notation in text:

The sums run over all pairs of atoms in an H-suppressed molecular graph:

where  is the number of non-H atoms and  is the entry in the ith row and the jth column of the distance matrix.

For  see 0 and for  see distance matrix.

Source:

·    Ivanciuc, O.; Balaban, T.-S.; Balaban, A. T. Design of Topological Indices. Part 4. Reciprocal Distance Matrix, Related Local Vertex Invariants and Topological Indices. J. Math. Chem. 1993, 12, 309-318

·    Plavsić, D.; Nikolić, S; Trinajstić, N.; Mihalić, Z. On the Harary Index for the Characterization of Chemical Graphs. J. Math. Chem. 1993, 12, 235-250

·    Lucić, B.; Milicević, A.; Nikolić, S; Trinajstić, N. Harary Index – Twelve Years Later. Croat. Chem. Acta 2002, 75, 847-867

·    TodCon, pages 209-210

76 total walk count

twc is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all lengths (from length  to length ) of walks in an H-suppressed molecular graph:

where  is the number of atoms and  is the molecular walk count of length k.

For  see 77-83.

Source:

·    Rücker, G.; Rücker, C. Counts of All Walks as Atomic and Molecular Descriptors. J. Chem. Inf. Comput. Sci. 1993, 33, 683-695

·    Rücker, G.; Rücker, C. Walk Counts, Labyrinthicity, and Complexity of Acyclic and Cyclic Graphs and Molecules. J. Chem. Inf. Comput. Sci. 2000, 40, 99-106

·    Gutman, I.; Rücker, C.; Rücker, G. On Walks in Molecular Graphs J. Chem. Inf. Comput. Sci. 2001, 41, 739-745

·    Nikolić, S; Trinajstić, N.; Tolić, I. M.; Rücker, G.; Rücker, C. On Molecular Complexity Indices. Chapter 2, pages 29-89 in Complexity in Chemistry (Bonchev, D.; Rouvray, D. H., Eds.), Taylor and Francis, London, 2003

·    TodCon, pages 480-482

77-83 molecular walk count of length k

mwc2, mwc3, mwc4, mwc5, mwc6, mwc7 and mwc8 are descriptors of the category 'topological'.

Notation in text: ; e.g.:

The sums run over all atoms in an H-suppressed molecular graph:

where  is the kth power of the adjacency matrix  (here not the descriptor : number of atoms) and  the number of atoms.

Remark:  is equal to the number of atoms,  is equal to .

For  see adjacency matrix, for  see 22.

Source:

·    Rücker, G.; Rücker, C. Counts of All Walks as Atomic and Molecular Descriptors. J. Chem. Inf. Comput. Sci. 1993, 33, 683-695

·    Rücker, G.; Rücker, C. Walk Counts, Labyrinthicity, and Complexity of Acyclic and Cyclic Graphs and Molecules. J. Chem. Inf. Comput. Sci. 2000, 40, 99-106

·    Gutman, I.; Rücker, C.; Rücker, G. On Walks in Molecular Graphs J. Chem. Inf. Comput. Sci. 2001, 41, 739-745

·    Nikolić, S; Trinajstić, N.; Tolić, I. M.; Rücker, G.; Rücker, C. On Molecular Complexity Indices. Chapter 2, pages 29-89 in Complexity in Chemistry (Bonchev, D.; Rouvray, D. H., Eds.), Taylor and Francis, London, 2003

·    TodCon, pages 480-482

84 unsaturated total walk count

twc_unsat is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all lengths (from length  to length ) of walks in an H-suppressed molecular graph:

where  is the number of atoms and  is the molecular walk count of length  derived from the “unsaturated” adjacency matrix, i. e. a matrix with entries  for multiple bonds.

For  see 85-91. See also unsaturated adjacency matrix.

Source:

·    No source. Definition is analogous to 76.

85-91 unsaturated molecular walk count of length k

mwc2_unsat, mwc3_unsat, mwc4_unsat, mwc5_unsat, mwc6_unsat, mwc7_unsat and mwc8_unsat are descriptors of the category 'topological'.

Notation in text: ; e.g.:

The sums run over all atoms in an H-suppressed molecular graph:

where  is the kth power of the unsaturated adjacency matrix  with entries  for multiple bonds, and  is the number of atoms.

For  see unsaturated adjacency matrix, for  see 22.

Source:

·    No source. Definition is analogous to 77-83.

92 gravitational index (pairs, topo. dist.)

G_1 (topo. dist.) is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all pairs of atoms in an H-suppressed molecular graph.

where  is the average weight of atom i (expressed in amu, i.e. 12.0110 for carbon) and  is the entry in the ith row and the jth column of the distance matrix.  is the number of atoms.

For  see distance matrix. For  see 0.

Source:

·    No source. Definition is analogous to 96 with topological distances.

93 gravitational index (pairs, topo. dist., incl. H atoms)

G_1 (topo. dist.,incl. H) is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all pairs of atoms in a molecular graph containing H atoms.

where  is the average weight of atom i and  is the entry in the ith row and the jth column of the distance matrix.  is the number of atoms.

For  see distance matrix. For  see 0.

Source:

·    No source. Definition is analogous to 97 with topological distances.

94 gravitational index (bonds, topo. dist.)

G_2 (topo. dist.) is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all edges of an H-suppressed molecular graph.

where  is the average weight of atom .

Source:

·    No source. Definition is analogous to 98 with topological distances.

95 gravitational index (bonds, topo. dist., incl. H atoms)

G_2 (topo. dist.,incl. H) is a descriptor of the category 'topological'.

Notation in text:

The sum runs over all edges of a molecular graph containing H atoms.

where  is the average weight of atom .

Source:

·    No source. Definition is analogous to 99 with topological distances.

96 gravitational index (pairs, 3D-dist.)

G_1 is a descriptor of the category 'geometrical'.

Notation in text:

The sum runs over all pairs of an H-suppressed molecular graph.

where  is the average weight of atom  and  is the interatomic distance (expressed in Ångström Å) of atom i and atom j.  is the number of atoms.

For  see 0.

Source:

·    Katritzky, A. R.; Mu L.; Lobanov, V. S.; Karelson, M. Correlation of Boiling Points with Molecular Structure. 1. A Training Set of 298 Diverse Organics and a Test Set of 9 Simple Inorganics. J. Phys. Chem. 1996, 100, 10400-10407

·    TodCon, page 412

97 gravitational index (pairs, 3D-dist., incl. H atoms)

G_1 (incl. H) is a descriptor of the category 'geometrical'.

Notation in text:

The sum runs over all pairs of atoms in a molecular graph containing H atoms.

where  is the average weight of atom  and  is the interatomic distance (expressed in Ångström Å) of atom i and atom j.  is the number of atoms.

For  see 0.

Source:

·    Katritzky, A. R.; Mu L.; Lobanov, V. S.; Karelson, M. Correlation of Boiling Points with Molecular Structure. 1. A Training Set of 298 Diverse Organics and a Test Set of 9 Simple Inorganics. J. Phys. Chem. 1996, 100, 10400-10407

·    TodCon, page 412

98 gravitational index (bonds, 3D-dist.)

G_2 is a descriptor of the category 'geometrical'.

Notation in text:

The sum runs over all edges of an H-suppressed molecular graph.

where  is the average weight of atom  and  is the interatomic distance (expressed in Ångström Å) of atom i and atom j.

Source:

·    Katritzky, A. R.; Mu L.; Lobanov, V. S.; Karelson, M. Correlation of Boiling Points with Molecular Structure. 1. A Training Set of 298 Diverse Organics and a Test Set of 9 Simple Inorganics. J. Phys. Chem. 1996, 100, 10400-10407

·    TodCon, page 412

99 gravitational index (bonds, 3D-dist., incl. H atoms)

G_2 (incl. H) is a descriptor of the category 'geometrical'.

Notation in text:

The sum runs over all edges of a molecular graph containing H atoms.

where  is the average weight of atom  and  is the interatomic distance (expressed in Ångström Å) of atom i and atom j.

Source:

·    Katritzky, A. R.; Mu L.; Lobanov, V. S.; Karelson, M. Correlation of Boiling Points with Molecular Structure. 1. A Training Set of 298 Diverse Organics and a Test Set of 9 Simple Inorganics. J. Phys. Chem. 1996, 100, 10400-10407

·    TodCon, page 412

100 Hosoya Z-index

Z is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms in the H-suppressed molecular graph and  is the number of sets of  mutually non-adjacent edges. , .

For  see 0, for  see 22.

Source:

·    Hosoya, H. Topological Index. A Newly Proposed Quantity Characterizing the Topological Nature of Structural Isomers of Saturated Hydrocarbons. Bull. Chem. Soc. Jpn. 1971, 44, 2332-2339

·    TodCon, page 215

·    Trin, page 132

101 Basak information content of order 0

IC_0, IC_1, IC_2, TIC_0, TIC_1, TIC_2, CIC_0, CIC_1, CIC_2, N*CIC_0, N*CIC_1, N*CIC_2, SIC_0, SIC_1, SIC_2, N*SIC_0, N*SIC_1, N*SIC_2, BIC_0, BIC_1, BIC_2, N*BIC_0, N*BIC_1 and N*BIC_2 are descriptors of the category 'topological'.

Notation in text: , , , , , , , , , , , , , , , , , , , , , , ,

For calculating these descriptors a molecular graph inclusive H atoms is considered.

Explanation:

Every atom is characterized by itself and its neighbours. Here the characterization of the ith atom itself depends on the atom number  and on the number of bonding electron pairs  (without H atoms). The characterization of the neighbourhood depends on the depth  of the neighbourhood (e.g.  for the next neighbours) and the characterization of the connected atoms and their bond multiplicities:

To calculate  only the characterization of the atoms is needed: C1, C2, C3, C4, C5 are C-atoms and have all

 

with  is the number of atoms and  is the number of bonds.

For  see 1, for  see 23.

Source:

·    Basak, S. C. Information Theoretic Indices of Neighborhood Complexity and Their Applications, chapter 12 in Topological Indices and Related Descripors in QSAR and QSPR (Devillers, J.; Balaban, A. T., Eds.) Gordon and Breach, Amsterdam, 1999

·    Basak, S. C. Use of Molecular Complexity Indices in Predictive Pharmacology and Toxicology: A QSAR Approach. Med. Sci. Res. 1987, 15, 605-609

·    Basak, S. C.; Gute, B. D. Characterization of Molecular Structures Using Topological Indices. SAR QSAR Environ. Res. 1997, 7, 1-21

102 Basak total information content of order 0

TIC_0 see 101.

103 Basak complementary information content of order 0

CIC_0 see 101.

104 total complementary information content of order 0

N*CIC_0 see 101.

105 Basak structural information content of order 0

SIC_0 see 101.

106 total structural information content of order 0

N*SIC_0 see 101.

107 bonding information content of order 0

BIC_0 see 101.

108 total bonding information content of order 0

N*BIC_0 see 101.

109 Basak information content of order 1

IC_1 see 101.

110 Basak total information content of order 1

TIC_1 see 101.

111 Basak complementary information content of order 1

CIC_1 see 101.

112 total complementary information content of order 1

N*CIC_1 see 101.

113 Basak structural information content of order 1

SIC_1 see 101.

114 total structural information content of order 1

N*SIC_1 see 101.

115 bonding information content of order 1

BIC_1 see 101.

116 total bonding information content of order 1

N*BIC_1 see 101.

117 Basak information content of order 2

IC_2 see 101.

118 Basak total information content of order 2

TIC_2 see 101.

119 Basak complementary information content of order 2

CIC_2 see 101.

120 total complementary information content of order 2

N*CIC_2 see 101.

121 Basak structural information content of order 2

SIC_2 see 101.

122 total structural information content of order 2

N*SIC_2 see 101.

123 bonding information content of order 2

BIC_2 see 101.

124 total bonding information content of order 2

N*BIC_2 see 101.

125 mean square distance index

MSD is a descriptor of the category 'topological'.

Notation in text:

The sums run over all atoms of an H-suppressed molecular graph:

where  is the number of non-H atoms and  is the entry in the ith row and the jth column of the distance matrix.

For  see 0 and for  see distance matrix.

Source:

·    Balaban, A. T. Topological Indices Based on Topological Distances in Molecular Graphs. Pure Appl. Chem. 1983, 55, 199-206

·    TodCon, page 113 (The formula given there is incorrect.)

126 detour index

w is a descriptor of the category 'topological'.

Notation in text:

The sums run over all atoms of an H-suppressed molecular graph:

where  is the number of non-H atoms and  is the entry in the ith row and the jth column of the detour matrix.

For  see 0 and for  see detour matrix.

Source:

·    Ivanciuc, O.; Balaban, A. T. Design of Topological Indices. Part 8. Path Matrices and Derived Molecular Graph Invariants. MATCH – Commun. Math. Comp. Chem. 1994, 30, 141-152

·    Amić, D.; Trinajstić, N. On the Detour Matrix. Croat. Chem. Acta. 1995, 68, 53-62

·    Lukovits, I. The Detour Index. Croat. Chem. Acta 1996, 69, 873-882

·    Lukovits, I.; Razinger, M. On Calculation of the Detour Index. J. Chem. Inf. Comput. Sci. 1997, 37, 283-286

·    TodCon, page 103

127 detour index (incl. half main diagonal)

w (incl. half diag.) is a descriptor of the category 'topological'.

Notation in text:

The sums run over all atoms of an H-suppressed molecular graph:

where  is the number of non-H atoms and  is the entry in the ith row and the jth column of the detour matrix containing diagonal elements .

For  see 0 and for  see detour matrix.

Source:

Rücker, G.; Rücker, C. Symmetry-Aided Computation of the Detour Matrix and the Detour Index. J. Chem. Inf. Comput. Sci. 1998, 38, 710-714

128-135 total acyclic path count and molecular acyclic path counts of length k

P_acyc, 2^P_acyc, 3^P_acyc, 4^P_acyc, 5^P_acyc, 6^P_acyc, 7^P_acyc, 8^P_acyc, 9^P_acyc and higher are descriptors of the category 'topological'.

Notation in text: , , , , , , , ,

where  is the number of paths of length  in the H-suppressed molecular graph without counting any closed paths (rings).  is the maximum length of all unclosed paths.

Source:

·    Randić, M.; Brissey, G. M.; Spencer, R. B.; Wilkins, C. L. Search for All Self-Avoiding Paths for Molecular Graphs. Comput. & Chem. 1979, 3, 5-13

·    Randić, M. Characterization of Atoms, Molecules, and Classes of Molecules Based on Paths Enumeration. MATCH – Commun. Math. Comp. Chem. 1979, 7, 5-64

·    TodCon, page 344

136 molecular acyclic path count of length 9 and higher

9^P_acyc and higher see 128-135.

137-144 total path count and molecular path counts of length k

P, 2^P, 3^P, 4^P, 5^P, 6^P, 7^P, 8^P, 9^P and higher are descriptors of the category 'topological'.

Notation in text: , , , , , , , ,

where  is the number of paths of length  in the H-suppressed molecular graph including closed paths (rings).  is the maximum length of all paths.

Source:

·    Randić, M.; Brissey, G. M.; Spencer, R. B.; Wilkins, C. L. Search for All Self-Avoiding Paths for Molecular Graphs. Comput. & Chem. 1979, 3, 5-13

·    Randić, M. Characterization of Atoms, Molecules, and Classes of Molecules Based on Paths Enumeration. MATCH – Commun. Math. Comp. Chem. 1979, 7, 5-64

·    TodCon, page 344

145 molecular path count of length 9 and higher

9^P and higher see 137-144.

146-152 total ring count and molecular ring count of length k

rings, 3^rings, 4^rings, 5^rings, 6^rings, 7^rings, 8^rings, 9^rings and higher are descriptors of the category 'topological'.

Notation in text: , , , , , , ,

where  is the number of rings of length (size)  in the H-suppressed molecular graph.  is the maximum size of all rings.

Source:

·    TodCon, page 94

153 molecular ring count of length 9 and higher

9^rings and higher see 146-152.

154 moment of inertia A

I_A, I_B, I_C are descriptors of the category 'geometrical'.

Notation in text: , ,

,  and  are the three principal moments of inertia of the molecule with .

Source:

·    TodCon, page 352

155 moment of inertia B

I_B see 154.

156 moment of inertia C

I_C see 154.

157-164 topological charge index of order k

ch. G_1, ch. G_2, ch. G_3, ch. G_4, ch. G_5, ch. G_6, ch. G_7, ch. G_8 are descriptors of the category 'topological’.

Notation in text: , , , , , , ,

The sums run over all atoms in an H-suppressed molecular graph.

where  is the charge term matrix,  is the number of atoms,  is the distance from atom  to atom , , and is the Kronecker delta:

For  see 0, for  see distanc matrix, for  see charge term matrix.

Source:

·    Gálvez, J.; Garcìa, R.; Salabert, M. T.; Soler, R. Charge Indexes. New Topologcal Descriptors. J. Chem. Inf. Comput. Sci. 1994, 34, 520-525

·    Gálvez , J.; Garcìa-Domenech, R.; De Julián-Ortiz, V.; Soler, R. Topological Approach to Drug Design. J. Chem. Inf. Comput. Sci. 1995, 35, 272-284

·    TodCon, pages 445-446

165-172 mean topological charge index of order k

ch. J_1, ch. J_2, ch. J_3, ch. J_4, ch. J_5, ch. J_6, ch. J_7, ch. J_8 and ch. J [5] are descriptors of the category 'topological'.

Notation in text: , , , , , , , ,

, mean topological charge index

, global topological charge index

where  is the number of atoms, , and  is the topological charge index of order .

For  see 157, for  see 0.

Source:

·    Gálvez, J.; Garcìa, R.; Salabert, M. T.; Soler, R. Charge Indexes. New Topologcal Descriptors. J. Chem. Inf. Comput. Sci. 1994, 34, 520-525

·    Gálvez , J.; Garcìa-Domenech, R.; De Julián-Ortiz, V.; Soler, R. Topological Approach to Drug Design. J. Chem. Inf. Comput. Sci. 1995, 35, 272-284

·    TodCon, pages 445-446

173 global topological charge index

ch. J [5] see 165-172.

174 Crippen slog P

slog P is a descriptor of the category 'miscellaneous'.

Notation in text:

where  is the number of atoms of Crippen type ,  is an increment for the  hydrophobicity of atom type . Structure-based types are attributed to atoms using a special table.

Source:

·    Wildman, S. A.; Crippen, G. M. Prediction of Physicochemical Parameters by Atomic Contributions J. Chem. Inf. Comput. Sci. 1999, 39, 868-873

175 Crippen sMR

sMR is a desriptor of the category 'miscellaneous'.

Notation in text:

where  is the number of atoms of Crippen type ,  is an increment for the molar refractivity of atom type . Structure-based types are attributed to atoms using a special table.

Source:

·    Wildman, S. A.; Crippen, G. M. Prediction of Physicochemical Parameters by Atomic Contributions J. Chem. Inf. Comput. Sci. 1999, 39, 868-873

176 steric energy

st. energy is a descriptor of the category 'geometrical'.

Notation in text:

This is the steric energy, as calculated by molecular mechanics in MOLGEN.

177 diameter

D is a descriptor of the category 'topological'.

Notation in text:  

is the short name of the topological diameter:

where  is the number of atoms in the H-suppressed molecular graph and  is an entry in the distance matrix.

For  see 0 and for  see distance matrix.

Source:

·    TodCon, page 112

178-245 Crippen atom type Xxnn

at C01- at C27, at H01- at H04, at O01- at O12, at N01- at N14, at Hal, at Cl, at Br, at I, at F, at P, at S01- at S03, at Me01, at Me02 are descriptors of the category 'miscellaneous'.

Notation in text: , , …, , …,

Source:

·    Wildman, S. ; Crippen, G. M. A. Prediction of Physicochemical Parameters by Atomic Contributions J. Chem. Inf. Comput. Sci. 1999, 39, 868-873

246 sum of subgraphs of order 0 to 8

0-8^K is a descriptor of the category 'overall'.

Notation in text:

where  is the number of subgraphs of  edges.

For  see 247-255.

Source:

·    Bonchev, D. Novel Indices for the Topological Complexity of Molecules. SAR QSAR Environ. Res. 1997, 7, 23-43

·    Rücker, G.; Rücker, C. Automatic Enumeration of All Connected Subgraphs. MATCH – Commun. Math. Comp. Chem. 2000, 41, 145-149

247-255 subgraphs of order k

0^K, 1^K, 2^K, 3^K, 4^K, 5^K, 6^K, 7^K and 8^K are descriptors of the category 'overall'.

Notation in text: , , …,

where  is the H-suppressed molecular graph.

Source:

·    Bonchev, D. Novel Indices for the Topological Complexity of Molecules. SAR QSAR Environ. Res. 1997, 7, 23-43

·    Rücker, G.; Rücker, C. Automatic Enumeration of All Connected Subgraphs. MATCH – Commun. Math. Comp. Chem. 2000, 41, 145-149

256 eccentric connectivity index

Xi^c is a descriptor of the category 'topological'.

Notation in text:

where  is the maximum entry in the ith line of the distance matrix.  is the vertex degree of atom .

For  see vertex degree, for  see eccentricity.

Source:

·    Sharma, V.; Goswami, R.; Madan, A. K. Eccentric Conectivity Index: A Novel Highly Discriminating Topological Descriptor for Structure-Property and Structure-Activity Studies J. Chem. Inf. Comput. Sci. 1997, 37, 273-282

·    TodCon, page 124

257 principal eigenvalue of A

lambda_1^A is a descriptor of the category 'topological'.

Notation in text:

 is the principal eigenvalue of the adjacency matrix .

For  see adjacency matrix.

Source:

·    TodCon, page 131

258 sum of coefficents of princ. eigenvec. of A

SCA1, SCA2 and SCA3 are descriptors of the category 'topological'.

Notation in text: , ,

The sum runs over all atoms of an H-suppressed molecule:

where  is the number of atoms,  is the ith coefficient of the eigenvector of the principal eigenvalue of . All coefficients in a principle eigenvector have the same sign, here always the positive sign is assumed.

The descriptors SCR2 and SCR3 are calculated analogously to VEA in TodCon, page 132.

For  see adjacency matrix.

Source:

·    Rücker, G.; Rücker, C.; Gutman, I. On Kites, Comets, and Stars. Sums of Eigenvector Coefficients in (Molecular) Graphs. Z. Naturforsch. A 2002, 57a, 143-153

259 mean coefficent of princ. eigenvec. of A

SCA2 see SCA1.

260 log of sum of coeff. of princ. eigenvec. of A

SCA3 see SCA1.

261 principal eigenvalue of D

lambda_1^D is descriptor of the category 'topological'.

Notation in text:

 is the principal eigenvalue of the distance matrix .

For  see distance matrix.

Source:

·    Schultz, H. P.; Schultz, E. B.; Schultz, T. P. Topological Organic Chemistry. 2. Graph Theory, Matrix Determinants and Eigenvalues, and Topological Indices of Alkanes. J. Chem. Inf. Comput. Sci. 1990, 30, 27-29

·    TodCon, page 134

262 total charge

cha is a descriptor of the category 'arithmetic'.

Notation in text:

 is the charge of the molecule.

263 number of radicals

n_rad is a descriptor of the category 'arithmetic'.

Notation in text:

 is the number of radical sites in a molecule.

264 total Chi index

Chi_T is a descriptor of the category 'topological'.

Notation in text:

The product runs over all atoms of an H-suppressed molecular graph.

where  is the vertex degree of atom .  is the number of atoms.

For  see vertex degree, for  see 0.

Source:

·    Needham, D. E.;Wei, I. C.; Seybold, P. G. Molecular Modeling of the Physical Properties of the Alkanes. J. Am. Chem. Soc. 1988, 110, 4186-4194

·    TodCon, page 86

265 number of methyl groups

T_m is a descriptor of the category 'topological'.

Notation in text:

 is the number of methyl groups in a molecular graph with H atoms.

Source:

·    Needham, D. E.;Wei, I. C.; Seybold, P. G. Molecular Modeling of the Physical Properties of the Alkanes. J. Am. Chem. Soc. 1988, 110, 4186-4194

266 number of pairs of methyl groups at distance 3

T_3 is a descriptor of the category 'topological'.

Notation in text:

 is the number of pairs of methyl groups at distance 3.

For  see 0 and for  see distance matrix.

Source:

·    Needham, D. E.;Wei, I. C.; Seybold, P. G. Molecular Modeling of the Physical Properties of the Alkanes. J. Am. Chem. Soc. 1988, 110, 4186-4194

267 number of hydrogen bond donors

HBD is a descriptor of the category 'arithmetic'.

Notation in text:

 is the number of H atoms attached to O and N atoms, in accord with the ACD definition.

Source:

·    STNotes 2002, 28, 3

·    TodCon, page 221-222

268 number of hydrogen bond acceptors

HBA is a descriptor of the category 'arithmetic'.

Notation in text:

 is the number of N and O atoms, in accord with the ACD definition.

Source:

·    STNotes 2002, 28, 3

·    TodCon, page 221-222

269 freely rotatable bonds

FRB is a descriptor of the category 'topological'.

Notation in text:

Source:

·    Veber, D. F.; Johnson, S. R.; Cheng, H.-Y.; Smith, B. R.; Ward, K. W.; Kopple, K. D. Molecular Properties that Influence the Oral Bioavailability of Drug Candidates. J. Med. Chem. 2002, 45, 2615-2623

·    TodCon, page 178

270 XY shadow

SHDW1, SHDW2 , SHDW3, SHDW4, SHDW5, SHDW6, SHDW1/ SHDW2, SHDW1/ SHDW3, SHDW2/ SHDW3, ssSHDW1, ssSHDW2 , ssSHDW3, ssSHDW4, ssSHDW5, ssSHDW6, ssSHDW1/ SHDW2, ssSHDW1/ SHDW3, ssSHDW2/ SHDW3 are descriptors of the category 'geometrical'.

Notation in text: , , , …, , …, ,

where ,  and  are the principle axes of inertia of the molecule (incl. H atoms). Each atom is projected using its vdw radius.

where ,  and  are the maximum dimension of the molecular surface in ,  and  direction using vdw radii.

Source:

·    Jurs, P. C.; Hasan, M. N.; Hansen, P. J.; Rohrbaugh, R. H. Prediction of Physicochemical Properties of Organic Compounds from Molecular Structure, pages 209-233 in Physical Property Prediction (Jochum, C., Ed.) Springer, Berlin 1988

·    Rohrbaugh, R. H.; Jurs, P. C. Description of Molecular Shape Applied in Studies of Structure/Activity and Structure/Property Relationships Anal. Chim. Acta 1987, 199, 99-109

·    Rohrbaugh, R. H.; Jurs, P. C. Molecular Shape and the Prediction of HPLC Retention Indexes of Polycyclic Aromatic Hydrocarbons Anal. Chem. 1987, 59, 1048-1054

·    TodCon, page 389

where  is the largest value,  is the second largest value, and   is the smallest value of  .   stands for size-sorted.

,  and  span the respective plane of projection.

Source:

·    TodCon, page 389

 

271 XZ shadow

SHDW2 see 270.

272 YZ shadow

SHDW3 see 270.

273 standardized XY shadow

SHDW4 see 270.

274 standardized XZ shadow

SHDW5 see 270.

275 standardized YZ shadow

SHDW6 see 270.

276 XY/XZ shadow

SHDW1/SHDW2 see 270.

277 XY/YZ shadow

SHDW1/SHDW3 see 270.

278 XZ/YZ shadow

SHDW2/SHDW3 see 270.

279 size sorted shadow 1

ssSHDW1 see 270.

280 size sorted shadow 2

ssSHDW2 see 270.

281 size sorted shadow 3

ssSHDW3 see 270.

282  size sorted standardized shadow 1

ssSHDW4 see 270.

283 size sorted standardized shadow 2

ssSHDW5 see 270.

284 size sorted standardized shadow 3

ssSHDW6 see 270.

285 size sorted shadow 1/2

ssSHDW1/SHDW2 see 270.

286 size sorted shadow 1/3

ssSHDW1/SHDW3 see 270.

287 size sorted shadow 2/3

ssSHDW2/SHDW3 see 270.

288 Van der Waals volume

V_vdw, density_vdw, V_vdw^s, V_cub are descriptors of the category 'geometrical'.

Notation in text: , , ,

, ,  and  are calculated for molecules including H atoms.

where ,  and  are the maximum dimensions of the molecular surface in ,  and  direction by using , where ,  and  are the principle axes of inertia of the molecule (incl. H atoms).

Source:

·    TodCon, page 326

289 density by Van der Waals volume

rho_vdw see 288.

290 standardized Van der Waals volume

V_vdw^s see 288.

291 enclosing cuboid

V_cub see 288.

292-371 Sum of E-state of atomic subgraphs

S(atomic subgraph) are descriptors of the category 'electrotopol./AI’;

e.g. S(sCH3) for subgraph: -CH3.

Notation in text: , …

 is the sum of electrotopological state values of all  subgraphs.

 

The S(sCH3) is descriptor 292. Here is the list of all E-state descriptors from 292 to 371:

 

292

S(sCH3)

312

S(sssNH)

332

S(aaS)

352

S(ssSiH2)

293

S(dCH2)

313

S(dsN)

333

S(dssS)

353

S(sssSiH)

294

S(ssCH2)

314

S(aaN)

334

S(ddssS)

354

S(ssssSi)

295

S(tCH)

315

S(sssN)

335

S(ssssssS)

355

S(sGeH3)

296

S(dsCH)

316

S(ddsN)

336

S(sCl)

356

S(ssGeH2)

297

S(aaCH)

317

S(aasN)

337

S(sSeH)

357

S(sssGeH)

298

S(sssCH)

318

S(ssssN)

338

S(dSe)

358

S(ssssGe)

299

S(ddC)

319

S(sOH)

339

S(ssSe)

359

S(sAsH2)

300

S(tsC)

320

S(dO)

340

S(aaSe)

360

S(ssAsH)

301

S(dssC)

321

S(ssO)

341

S(dssSe)

361

S(sssAs)

302

S(aasC)

322

S(aaO)

342

S(ddssSe)

362

S(sssdAs)

303

S(aaaC)

323

S(sF)

343

S(sBr)

363

S(sssssAs)

304

S(ssssC)

324

S(sPH2)

344

S(sI)

364

S(sSnH3)

305

S(sNH3)

325

S(ssPH)

345

S(sLi)

365

S(ssSnH2)

306

S(sNH2)

326

S(sssP)

346

S(ssBe)

366

S(sssSnH)

307

S(ssNH2)

327

S(dsssP)

347

S(ssssBe)

367

S(ssssSn)

308

S(dNH)

328

S(sssssP)

348

S(ssBH)

368

S(sPbH3)

309

S(ssNH)

329

S(sSH)

349

S(sssB)

369

S(ssPbH2)

310

S(aaNH)

330

S(dS)

350

S(ssssB)

370

S(sssPbH)

311

S(tN)

331

S(ssS)

351

S(sSiH3)

371

S(ssssPb)

 

where s means a single bond, ss two single bonds, d a double bonds, t a triple bond, a an aromatic bond, etc. connected to the specified atom, not counting the single bonds to the attached H atoms. H2 means two attached H atoms.

Source:

·    Kier, L. B.; Hall, L. H. Molecular Structure Description. The Electrotopological State. Academic Press, San Diego (California) and London, 1999

 

372 Szeged index

SZD, SZDp are indices of the category 'topological'.

Notation in text: ,

The sums run over an H-suppressed molecular graph:

where  is the number of atoms in the H-suppressed molecular graph and  is the Szeged matrix.

For  see 0 and for  see Szeged matrix.

Source:

·    Khadikar, P. V.; Deshpande, N.V.; Kale, P. P.; Dobrynin, A.; Gutman, I.; Dömötör, G. The Szeged Index and an Analogy with the Wiener Index. J. Chem. Inf. Comput. Sci., 1995, 35, 547-550

·    Gutman, I; Klavzar, S. An Algorithm for the Calculation of the Szeged Index of Benzenoid Hydrocarbons. J. Chem. Inf. Comput. Sci. 1995, 35, 1011-1014

·    Zerovnik, J. Computing the Szeged Index. Croat. Chem. Acta. 1996, 69, 837-843

·    Zerovnik, J. Szeged Index of Symmetric Graphs. J. Chem. Inf. Comput. Sci. 1999, 39, 77-80

·    TodCon, page 438

373 hyper-Szeged index

SZDp see 372.

374 Van der Waals surface

S_vdw is a descriptor of the category 'geometrical'.

Notation in text:

 is the surface of the molecule by using vdw radii for each atom.

375 solvent-accessible surface (H2O)

SASA H2O is a descriptor of the category 'geometrical'.

Notation in text:

 is the solvent accessible surface of the molecule by using vdw radii and an H2O molecule (r = 1.5Å) as a probe.

376 solvent-accessible surface (H)

SASA H is a descriptor of the category 'geometrical'.

Notation in text:

 is the solvent accessible surface of the molecule by using vdw radii and an H atom (r = 1.2Å) as a probe.

377-456 AI of atomic subgraph

AI(atomic subgraph) are descriptors of the category 'electrotopol./AI’;

eg. AI(sCH3) for subgraph: -CH3.

Notation in text: , …

The sums run over an H-suppressed molecular graph:

where  is the number of  subgraphs,  (or ) is the modified vertex degree of atom  and   is the vertex distance degree of atom .

For the subgraphs considered see 292-371, for  see modified vertex degree and for  see vertex distance degree.

 

The AI(sCH3) is descriptor 377. Here is the list of all AI descriptors from 377 to 456:

 

377

AI(sCH3)

397

AI(sssNH)

417

AI(aaS)

437

AI(ssSiH2)

378

AI(dCH2)

398

AI(dsN)

418

AI(dssS)

438

AI(sssSiH)

379

AI(ssCH2)

399

AI(aaN)

419

AI(ddssS)

439

AI(ssssSi)

380

AI(tCH)

400

AI(sssN)

420

AI(ssssssS)

440

AI(sGeH3)

381

AI(dsCH)

401

AI(ddsN)

421

AI(sCl)

441

AI(ssGeH2)

382

AI(aaCH)

402

AI(aasN)

422

AI(sSeH)

442

AI(sssGeH)

383

AI(sssCH)

403

AI(ssssN)

423

AI(dSe)

443

AI(ssssGe)

384

AI(ddC)

404

AI(sOH)

424

AI(ssSe)

444

AI(sAsH2)

385

AI(tsC)

405

AI(dO)

425

AI(aaSe)

445

AI(ssAsH)

386

AI(dssC)

406

AI(ssO)

426

AI(dssSe)

446

AI(sssAs)

387

AI(aasC)

407

AI(aaO)

427

AI(ddssSe)

447

AI(sssdAs)

388

AI(aaaC)

408

AI(sF)

428

AI(sBr)

448

AI(sssssAs)

389

AI(ssssC)

409

AI(sPH2)

429

AI(sI)

449

AI(sSnH3)

390

AI(sNH3)

410

AI(ssPH)

430

AI(sLi)

450

AI(ssSnH2)

391

AI(sNH2)

411

AI(sssP)

431

AI(ssBe)

451

AI(sssSnH)

392

AI(ssNH2)

412

AI(dsssP)

432

AI(ssssBe)

452

AI(ssssSn)

393

AI(dNH)

413

AI(sssssP)

433

AI(ssBH)

453

AI(sPbH3)

394

AI(ssNH)

414

AI(sSH)

434

AI(sssB)

454

AI(ssPbH2)

395

AI(aaNH)

415

AI(dS)

435

AI(ssssB)

455

AI(sssPbH)

396

AI(tN)

416

AI(ssS)

436

AI(sSiH3)

456

AI(ssssPb)

 

where s means a single bond, ss two single bonds, d a double bonds, t a triple bond, a an aromatic bond, etc. connected to the specified atom not counting the single bonds to the attached H atoms. H2 means two attached H atoms.

Source:

·  Ren, B. Novel Atomic-Level-Based AI Topological Descriptors: Application to QSPR/QSAR Modeling. J. Chem. Inf. Comput. Sci. 2002, 42, 858-868

·  Ren, B. Novel Atomic-Level-Based AI Topological Descriptors for Structure-Property Correlations. J. Chem. Inf. Comput. Sci. 2003, 43, 161-169

·  Ren, B. Novel Atom-Type AI Indices for QSPR Studies of Alcohols. Comput. & Chem. 2002, 26, 223-235

·  Ren, B. Application of Novel Atom-Type AI Topological Indices to QSPR Studies of Alkanes. Comput. & Chem. 2002, 26, 357-369

457 Xu index

Xu, Xu^m are descriptors of the category 'electrotopol./AI'.

Notation in text: ,

The sum runs over all atoms of an H-suppressed molecule:

where  is the number of atoms in an H-suppressed molecule,  is the vertex degree of the ith atom,  is the vertex distance degree of the ith atom.  (or ) is the modified vertex degree of atom .

For  see 0, for  see vertex degree, for  see vertex distance degree and for  see modified vertex degree.

Source:

·    Ren, B. A New Topological Index for QSPR of Alkanes. J. Chem. Inf. Comput. Sci. 1999, 39, 139-143

·    TodCon, page 507

458 modified Xu index

Xu^m see 457.

459-488 connectivity indices for substructures

m^Chi_q and m^Chi^v_q are descriptors of the category 'topological'. Substructures are paths, clusters, path-clusters and chains.

 

Available are:

459

3^Chi_p

469

6^Chi_pc

479

4^Chi^v_c

460

4^Chi_p

470

3^Chi_ch

480

5^Chi^v_c

461

5^Chi_p

471

4^Chi_ch

481

6^Chi^v_c

462

6^Chi_p

472

5^Chi_ch

482

4^Chi^v_pc

463

3^Chi_c

473

6^Chi_ch

483

5^Chi^v_pc

464

4^Chi_c

474

3^Chi^v_p

484

6^Chi^v_pc

465

5^Chi_c

475

4^Chi^v_p

485

3^Chi^v_ch

466

6^Chi_c

476

5^Chi^v_p

486

4^Chi^v_ch

467

4^Chi_pc

477

6^Chi^v_p

487

5^Chi^v_ch

468

5^Chi_pc

478

3^Chi^v_c

488

6^Chi^v_ch

 

Notation in text: ,

where  is the vertex degree and  is the valence vertex degree of atom  of the subgraph of type  in the H-suppressed molecular graph.  is the order (this is also called the “size” or “the number of edges”) of the subgraphs considered.  means paths, clusters, path-clusters or chains.  is the number of subgraphs of type  and size .  is the number of atoms of the subgraph considered.

 

Type of subgraphs:

·    If a subgraph contains a cycle it is of type chain () for ,

·    otherwise if every vertex has one or more than two non-H neighbours it is of type cluster () for ,

·    otherwise if every vertex has one or two non-H neighbours it is of type path () for ,

·    otherwise it is of type path-cluster () for . So a path-cluster has no cycles but vertices with one, two and more than two non-H neighbours.

 

For example paths are:

path

3

4

5

 

For example chains are:

chain

3

4

4

 

For example clusters are:

cluster

3

4

5

 

For example path-clusters are:

path-cluster

4

6

6

 

For  see vertex degree, for  see valence vertex degree.

Source:

·    Kier, L. B.; Hall L. H. The Nature of Structure-Acticity Relationships and their Relation to Molecular Connectivity. Eur. J. Med. Chem., 1977, 12, 307-312

·    Kier, L. B.; Hall L. H. Molecular Connectivity in Structure-Activity Analysis. Research Studies Press - Wiley, Chichester (UK), 1986.

·    TodCon, pages 84-86 and page 314

489-699 overall indices

m^TO, m^TO*, m^TO_q, m^TO*_q, TO, TO*, TO_q, TO*_q are descriptors of the category 'overall'.

 

Available are:

489

0^TC                     

542

2^TW                     

595

5^TC*_c                  

648

4^TM_2_pc               

490

1^TC                     

543

3^TW                      

596

6^TC*_c                  

649

5^TM_2_pc               

491

2^TC                     

544

4^TW                     

597

TC*_c                    

650

6^TM_2_pc               

492

3^TC                     

545

5^TW                      

598

3^TC^v_c                 

651

TM_2_pc                 

493

4^TC                     

546

6^TW                     

599

4^TC^v_c                 

652

4^TM_2*_pc              

494

5^TC                     

547

TW                       

600

5^TC^v_c                 

653

5^TM_2*_pc              

495

6^TC                     

548

3^TC_p                   

601

6^TC^v_c                 

654

6^TM_2*_pc              

496

TC                       

549

4^TC_p                   

602

TC^v_c                    

655

TM_2*_pc                

497

1^TC*                    

550

5^TC_p                   

603

3^TM_1_c                 

656

4^TW_pc                 

498

2^TC*                    

551

6^TC_p                   

604

4^TM_1_c                  

657

5^TW_pc                 

499

3^TC*                    

552

TC_p                     

605

5^TM_1_c                 

658

6^TW_pc                 

500

4^TC*                    

553

3^TC*_p                  

606

6^TM_1_c                  

659

TW_pc                   

501

5^TC*                    

554

4^TC*_p                  

607

TM_1_c                   

660

3^TC_ch                 

502

6^TC*                    

555

5^TC*_p                  

608

3^TM_1*_c                

661

4^TC_ch                 

503

TC*                      

556

6^TC*_p                  

609

4^TM_1*_c                

662

5^TC_ch                 

504

0^TC^v                   

557

TC*_p                    

610

5^TM_1*_c                

663

6^TC_ch                  

505

1^TC^v                   

558

3^TC^v_p                 

611

6^TM_1*_c                

664

TC_ch                   

506

2^TC^v                   

559

4^TC^v_p                 

612

TM_1*_c                  

665

3^TC*_ch                 

507

3^TC^v                   

560

5^TC^v_p                 

613

3^TM_2_c                 

666

4^TC*_ch                

508

4^TC^v                   

561

6^TC^v_p                 

614

4^TM_2_c                 

667

5^TC*_ch                

509

5^TC^v                   

562

TC^v_p                   

615

5^TM_2_c                 

668

6^TC*_ch                

510

6^TC^v                   

563

3^TM_1_p                 

616

6^TM_2_c                 

669

TC*_ch                  

511

TC^v                     

564

4^TM_1_p                 

617

TM_2_c                   

670

3^TC^v_ch               

512

0^TM_1                   

565

5^TM_1_p                 

618

3^TM_2*_c                

671

4^TC^v_ch               

513

1^TM_1                    

566

6^TM_1_p                 

619

4^TM_2*_c                

672

5^TC^v_ch               

514

2^TM_1                   

567

TM_1_p                   

620

5^TM_2*_c                

673

6^TC^v_ch               

515

3^TM_1                    

568

3^TM_1*_p                

621

6^TM_2*_c                

674

TC^v_ch                 

516

4^TM_1                   

569

4^TM_1*_p                

622

TM_2*_c                  

675

3^TM_1_ch               

517

5^TM_1                   

570

5^TM_1*_p                

623

3^TW_c                   

676

4^TM_1_ch               

518

6^TM_1                   

571

6^TM_1*_p                

624

4^TW_c                   

677

5^TM_1_ch               

519

TM_1                     

572

TM_1*_p                  

625

5^TW_c                   

678

6^TM_1_ch               

520

1^TM_1*                  

573

3^TM_2_p                 

626

6^TW_c                   

679

TM_1_ch            

521

2^TM_1*                  

574

4^TM_2_p                  

627

TW_c                    

680

3^TM_1*_ch              

522

3^TM_1*                  

575

5^TM_2_p                 

628

4^TC_pc                 

681

4^TM_1*_ch              

523

4^TM_1*                  

576

6^TM_2_p                 

629

5^TC_pc                 

682

5^TM_1*_ch              

524

5^TM_1*                  

577

TM_2_p                   

630

6^TC_pc                 

683

6^TM_1*_ch              

525

6^TM_1*                  

578

3^TM_2*_p                

631

TC_pc                   

684

TM_1*_ch                

526

TM_1*                    

579

4^TM_2*_p                

632

4^TC*_pc                

685

3^TM_2_ch               

527

1^TM_2                   

580

5^TM_2*_p                

633

5^TC*_pc                 

686

4^TM_2_ch               

528

2^TM_2                   

581

6^TM_2*_p                

634

6^TC*_pc                

687

5^TM_2_ch               

529

3^TM_2                   

582

TM_2*_p                  

635

TC*_pc                  

688

6^TM_2_ch               

530

4^TM_2                   

583

3^TW_p                   

636

4^TC^v_pc               

689

TM_2_ch                 

531

5^TM_2                   

584

4^TW_p                   

637

5^TC^v_pc               

690

3^TM_2*_ch              

532

6^TM_2                   

585

5^TW_p                   

638

6^TC^v_pc               

691

4^TM_2*_ch              

533

TM_2                     

586

6^TW_p                   

639

TC^v_pc                 

692

5^TM_2*_ch               

534

1^TM_2*                  

587

TW_p                     

640

4^TM_1_pc               

693

6^TM_2*_ch              

535

2^TM_2*                  

588

3^TC_c                   

641

5^TM_1_pc               

694

TM_2*_ch                

536

3^TM_2*                  

589

4^TC_c                   

642

6^TM_1_pc               

695

3^TW_ch                 

537

4^TM_2*                  

590

5^TC_c                   

643

TM_1_pc                 

696

4^TW_ch                 

538

5^TM_2*                  

591

6^TC_c                   

644

4^TM_1*_pc              

697

5^TW_ch                 

539

6^TM_2*                  

592

TC_c                     

645

5^TM_1*_pc              

698

6^TW_ch                 

540

TM_2*                     

593

3^TC*_c                  

646

6^TM_1*_pc              

699

TW_ch                   

541

1^TW

594

4^TC*_c

647

TM_1*pc

 

 

Notation in text: , , , , , , ,

 is the overall-index sign. For the molecule each connected subgraph up to size  is constructed.  is one of these: M_1 for first Zagreb index , M_2 for second Zagreb index , W for Wiener index . C represents the sum over vertex degree  of each atom . C^v represents the sum over valence vertex degree  of each atom .

where  is the order (this is also called the “size” or “the number of edges”) of the subgraphs of the H-suppressed molecular graph; if  is specified (as path, cluster, path-cluster, chain), only subgraphs of this type are used (see 459-488).

 

The sums run over the subgraphs (regarding  and  if denoted) and sum up the values of the indices specified (e.g. W for Wiener index) of the subgraphs. In , ,  calculations the  values of the vertices of the subgraphs are used. If no asterisk appears in the symbol of an index, then these are taken as they are in the parent graph. If an asterisk appears in the symbol of an index, then the  values are taken as they are in the respective isolated subgraph.

For  see 45, for  see 46, for  see 44, for  see vertex degree, for  see valence vertex degree.

Source:

·    Bonchev, D.; Trinajstić, N. Overall Molecular Descriptors. 3. Overall Zagreb Indices. SAR QSAR Environ. Res. 2001, 12, 213-236

·    Bonchev, D. The Overall Wiener Index – A New Tool for Characterization of Molecular Topology. J. Chem. Inf. Comput. Sci. 2001, 41, 582-592

·    Bonchev, D. Overall Connectivity – A Next Generation Molecular Connectivity. J. Mol. Graphics Model. 2001, 20, 65-75

·    Bonchev, D. Overall Connectivities/Topological Complexities: A New Powerful Tool for QSPR/QSAR. J. Chem. Inf. Comput. Sci. 2000, 40, 934-941

701 topological radius

R is a descriptor of the category 'topological'.

Notation in text:

where  is the number of atoms in the H-suppressed molecular graph and  is an entry of the distance matrix.

For  see 0 and for  see distance matrix.

Source:

TodCon, page 112

702 number of connectivity components

con.comp. is a descriptor of the category 'topological'.

Notation in text:

In most cases, this index is equal to 1. If the compund is made of more than one component, the index increases.

703 graph-theoretical planarity

gt planar is a descriptor of the category 'topological'.

Notation in text:

Source:

·    Rücker, C.; Meringer, M. How Many Organic Compunds are gt-nonplanar? MATCH-Commun. Math. Comput. Chem. 2002, 45, 159-172

704 geometrical diameter

D_3D is a descriptor of the category 'geometrical'.

Notation in text:

 is the maximum distance of two points on the vdw-surface of the molecule incl. H atoms:

For vdw-surface see 374.

705 enclosing sphere

V_sphere is a descriptor of the category 'geometrical'.

Notation in text:

 is the volume of the enclosing sphere (incl. vdw-radii) of the molecule incl. H atoms:

For vdw-radii see 288, for  see 704.

706 relative number of rings

rel. N_rings is a descriptor of the category 'topological'.

Notation in text:

 is the relative number of rings. It is relative to the number of atoms of an H-suppressed molecule:

where  is the number of rings.

For  see 146-152. For  see 0.

707 relative cyclomatic number

rel. C is a descriptor of the category 'topological'.

Notation in text:

 is the relative cyclomatic number. It is relative to the number of atoms of an H-suppressed molecule:

where  is the cyclomatic number.

For  see 39. For  see 0.


 

Some auxiliary structures for calculating descriptors

adjacency matrix

The adjacency matrix  (not to be confused with the descriptor number of atoms ) is defined as:

alpha

The modifying term  (in e.g. Kier and Hall shape and flexibility indices, see 65-68) is defined as:

where  is the covalent radius of the ith atom in an H-suppressed molecule and  is the covalent radius of a sp3 carbon atom:

 

Atom / Hybrid

Atom / Hybrid

 

Csp3

0.77

 

0.00

 

 

Psp3

1.10

 

0.43

 

 

Csp2

0.67

 

-0.13

 

 

Psp2

1.00

 

0.30

 

 

Csp

0.60

 

-0.22

 

 

Ssp3

1.04

 

0.35

 

 

Nsp3

0.74

 

-0.04

 

 

Ssp2

0.94

 

0.22

 

 

Nsp2

0.62

 

-0.20

 

 

F

0.72

 

-0.07

 

 

Nsp

0.55

 

-0.29

 

 

Cl

0.99

 

0.29

 

 

Osp3

0.74

 

-0.04

 

 

Br

1.14

 

0.48

 

 

Osp2

0.62

 

-0.20

 

 

I

1.33

 

0.73

 

Source: TodCon, page 250

charge term matrix

 is a square matrix of dimension , where  is the number of rows (and columns).  is equal to the descriptor  (number of non-H atoms). Entries are the integers …, -1, 0, 1, 2, … .  is calculated by matrix and the vertex degree :

with  is defined as:

where  is the adjacency matrix, matrix  is defined by the entries in the distance matrix :

For  see vertex degree, for  see adjaceny matrix, for  and  see distance matrix.

detour matrix

 is a square matrix of dimension , where  is the descriptor  (number of non-H atoms). Entries are 0, 1, 2, …

An entry  represents the length of the longest path from atom (vertex)  to atom (vertex)  in a molecular graph without H atoms. Many authors set  for all vertices :

There is also a detour matrix  which includes closed detours (rings of maximal length) from atom i to itself:

 

For  see 0.

Source:

Buckley, F.; Harary F. Distance in Graphs. Addison-Wesley, Redwood City California, 1990, page 213

Ivanciuc, O.; Balaban, A. T. Design of Topological Indices. Part 8. Path Matrices and Derived Molecular Graph Invariants. MATCH - Commun. Math. Comp. Chem. 1994, 30, 141-152

Rücker, G.; Rücker, C. Symmetry-Aided Computation of the Detour Matrix and the Detour Index. J. Chem. Inf. Comput. Sci. 1998, 38, 710-714

TodCon, page 103

distance matrix, distance

 is a square matrix of dimension , where  is the descriptor  (number of non-H atoms). Entries are 0, 1, 2, …

An entry  represents the length of the shortest path from atom (vertex)  to atom (vertex)  in an H-supressed molecular graph.

 is also called the distance of atom  to atom .

For  see 0.

eccentricity

 is the maximum entry in the ith line of the distance matrix of an H-suppressed graph:

 is the distance of atom i to atom j.  is the number of atoms.

For  see 0. For  see distance matrix.

Source:

·    TodCon, page 112

modified vertex degree

 (or ) in e.g. Ren’s AI indices (see 377-456) is the modified vertex degree of the atom  in an H-suppressed molecule. It is defined as the number of neighbours of atom  (=) modified by the value .

where  is defined as:

where  is the number of atoms,  is the number of H atoms attached to atom ,  is the number of valence electrons of atom  and  is the atomic number of atom .

See also valence vertex degree.

For  see vertex degree, for  see 0.

Szeged matrix

 is a square matrix of dimension , where  is equal to the descriptor  (number of non-H atoms). Entries are 0, 1, 2, …

A entry  is the number of atoms being closer to  than to :

Source:

·    TodCon, page 438

unsaturated adjacency matrix

The unsaturated adjacency matrix  is defined as:

unsaturated vertex distance degree

 is defined as the ith row sum of the unsaturated distance matrix  of an H-suppressed molecular graph:

 

For  see 0. For  and  see unsaturated distance matrix.

unsaturated distance matrix

 is a square matrix of dimension , where  is equal to the descriptor  (number of non-H atoms).

An entry  represents the length of the shortest path from atom (vertex) i to atom (vertex) j in a H-supressed molecular graph. Single bonds represent a distance of 1, double bonds represent a distance of , triple bonds represent a distance of , aromatic bonds represent a distance of :

In this example, the distance  from  to  is  and the distance  is .

For  see 0.

valence vertex degree

 is the valence vertex degree of atom  in an H-suppressed molecule:

with  is the number of valence electrons of atom ,  is the number of H atoms attached to atom , and  is the total number of electrons (= the atomic number) of atom .

vertex degree

 is the vertex degree of atom  in an H-suppressed molecule. It is defined as the number of neighbours of atom , which is the ith row sum of the adjacency matrix

where  is equal to the descriptor  (number of non-H atoms).

vertex distance degree

 is defined as the ith row sum of the distance matrix  of an H-suppressed molecular graph:

For  see 0. For  and  see distance matrix.

 

© OLGEN exit by Joachim Braun and Christoph Rücker