Table 1.

Descriptors used.

Symbol	Name	Definition	Reference
N	Molecular size	Number of non-hydrogen atoms.	[68]
Vk k = 3, 4	Vertices of degree k	Number of atoms having k bonds, σ or π, to non-hydrogen atoms.	[68]
R	Ramification	Number of single structural branches.	[68]
W	Wiener path number	Sum of the distances between any two atoms in terms of bonds.	[100]
L	Length	Maximal distance between atoms in terms of bonds.	[68]
PRk k = 0–3	Pairs of ramifications at distance k	Number of pairs of single branches at distance k in terms of bonds.	[68]
kχt k = 0–4 t = p, c, pc	Randić-like indices of order k and type path (p), cluster (c) and path-cluster (pc)	${}_{ }{}^k\chi {}_t={\displaystyle {\displaystyle \sum }_{j=1}^{{}_{ }{}^{k}n{}_t}}{\left({\displaystyle {\displaystyle \prod }_{i\in S_j}}{\delta }_i\right)}^{\raisebox{1ex}{$-1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$ δi, number of bonds, σ or π, of the atom i to non-hydrogen atoms. Sj, jth sub-structure of order k and type t.	[71,81,82]
kχtv k = 0–4 t = p, c, pc	Kier-Hall indices of order k and type path (p), cluster (c) and path-cluster (pc)	${}_{ }{}^k\chi {{}_t}^V={\displaystyle {\displaystyle \sum }_{j=1}^{{}_{ }{}^{k}n{}_t}}{\left({\displaystyle {\displaystyle \prod }_{i\in S_j}}{\delta }_i{}^V\right)}^{\raisebox{1ex}{$-1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$ δiv, Kier-Hall valence of the atom i. Sj,jth sub-structure of order k and type t.	[71,81,82]
Gk k = 1–5	Topological charge indices of order k	$G_k={\displaystyle {\displaystyle \sum }_{i=1}^{N-1}{\displaystyle \sum }_{j=i+1}^N}\left|M_{ij}-M_{ji}\right|\delta \left(k,D_{ij}\right)$ $M=AQ$, product of the adjacency and inverse squared distance matrices for the hydrogen-depleted molecular graph. D, distance matrix. δ, Kronecker delta.	[68,101]
Gkv k = 1–5	Valence topological charge indices of order k	$G_k{}^V={\displaystyle {\displaystyle \sum }_{i=1}^{N-1}{\displaystyle \sum }_{j=i+1}^N}\left|M_{ij}{}^V-M_{ji}{}^V\right|\delta \left(k,D_{ij}\right)$ $M^V=A^{V}Q,$ product of the electronegativity-modified adjacency and inverse squared distance matrices for the hydrogen-depleted molecular graph. D, distance matrix. δ, Kronecker delta.	[68,101]
Jk k = 1–5	Pondered topological charge indices of order k	$J_k=\frac{G_k}{N-1}$	[68,101]
Jkv k = 1–5	Pondered valence topological charge indices of order k	$J_k{}^V=\frac{G_k{}^V}{N-1}$	[68,101]
kDt k = 0–4 t = p, c, pc	Connectivity differences of order k and type path (p), cluster (c) and path-cluster (pc)	${}_{ }{}^{k}D{}_t={}_{ }{}^k\chi {}_t-{}_{ }{}^k\chi {{}_t}^V$	[68]
Ek k = 1–5	Topological charge differences of order k	$E_k=G_k{}^V-G_k$	[102]
Fk k = 1–5	Pondered topological charge differences of order k	$F_k=J_k{}^V-J_k$	[102]
kCt k = 0–4 t = p, c, pc	Connectivity quotients of order k and type path (p), cluster (c) and path-cluster (pc)	${}_{ }{}^{k}C{}_t=\frac{{}_{ }{}^k\chi {}_t}{{}_{ }{}^k\chi {{}_t}^V}$	[68]
kQt k = 0–4 t = p, c, pc	Inverse connectivity quotients of order k and type path (p), cluster (c) and path-cluster (pc)	${}_{ }{}^{k}Q{}_t=\frac{{}_{ }{}^k\chi {{}_t}^V}{{}_{ }{}^k\chi {}_t}$	[102]
CGk k = 1–5	Topological charge quotients of order k	$C{G}_k=\frac{G_k}{G_k{}^V}$	[102]
QGk k = 1–5	Inverse topological charge quotients of order k	$Q{G}_k=\frac{G_k{}^V}{G_k}$	[102]