Inverse Sum Indeg Index (Energy) with Applications to Anticancer Drugs

For a simple graph with vertex set (Formula presented.) with degree sequence (Formula presented.) of vertex (Formula presented.), the inverse sum indeg matrix ((Formula presented.) -matrix) (Formula presented.) of G is defined by (Formula presented.) if (Formula presented.) is adjacent to (Formula presented.), and zero, otherwise. The multiset of eigenvalues of (Formula presented.) is the (Formula presented.) -spectrum of G and the sum of their absolute values is the (Formula presented.) -energy of (Formula presented.). In this paper, we modify the two results of (Li, Ye and Broersma, 2022), give the correct characterization of the extremal graphs and thereby obtain better bounds than the already known results. Moreover, we also discuss the QSPR analysis and carry the statistical modelling (linear, logarithmic and quadratic) of the physicochemical properties of anticancer drugs with the (Formula presented.) -index (energy).