Abstract

The general harmonic index and general sum-connectivity index are two degree-based topological indices which reflect certain structural features of organic molecules. A fluoranthene-type benzenoid system (f-benzenoid) is a polycyclic conjugated system obtained by joining two ordinary benzenoid hydrocarbons so as to form a five-membered ring. In this paper, by virtue of molecular structural analysis, we give the expressions for computing the general harmonic index and general sum-connectivity index of f-benzenoids, and we determine the extremal values of general harmonic index $H_{\alpha }$ and general sum-connectivity index $S_{\alpha }$ in f-benzenoids with h hexagons for some real number α. Especially, we give the extremal values of $H_{\alpha }$ and $S_{\alpha }$ in cata-catacondensed f-benzenoids with h hexagons.

摘要

一般谐波指数和一般总和连通指数是反映有机分子某些结构特征的基于度的两个拓扑指数。荧蒽型苯系( f -benzenoid )是由两个普通苯系烃连接形成五元环而得到的多环共轭系。本文通过分子结构分析，给出了f-苯类的一般调和指数和总和连通指数的计算表达式，并确定了一般调和指数的极值。$H_{\alpha }$和一般总和连通性指数${\mathrm{小号}}_{\alpha }$在带有 h 六边形的f -benzenoids 中，对于某个实数 α。特别是，我们给出的极值$H_{\alpha }$和${\mathrm{小号}}_{\alpha }$在具有 h 六边形的 cata-catacondensed f -benzenoids 中。