【摘要】 建议了一种新的拓扑指数Ｆ２，并用Ｆ２研究了ＡＢｎ（ｎ＝２，３，４，５）型分子的平均键能。研究表明，Ｆ２与ＡＢｎ型分子的平均键能呈良发的线性关系，并得出了ＡＢ３、ＡＢ４、ＡＢ５、型分子键长与平均键能关系的数学表达式更多还原

【Abstract】 This paper proposed a new topological index F 2.TheF 2 of AB n molecules were calculated.The linear least squar regressian shows that correletion ship between F 2 and the average bond energies of the molecules is excellent.Three formulae which calculated the bond energies from the bond lengths of AB 3,AB 4,AB 5molecules were obtained,respectively.更多还原