Extremal Values of the General Harmonic Index and General Sum-Connectivity Index of f-Benzenoids

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.

Keywords:

• Cata-catacondensed f-benzenoid
• f-benzenoid
• general Harmonic index
• general sum-connectivity index
• inlet

Additional information

Funding

This work was supported by Natural Science Foundation of Zhejiang Province (China) (No. LY17A010017). The authors are very thankful to anonymous referees for their constructive suggestions and critical comments, which led to this improved version.