On the Szeged Index of Unbranched Catacondensed Benzenoid Molecules

The Szeged index (Sz) of unbranched catacondensed benzenoid (UBCB) hydrocarbons is examined. An efficient method for the calculations of their Sz is put forward. Among the UBCB molecules with a fixed number of hexagons, the linear polyacene has a rnaximal and the helicene a minimal Sz