【摘要】 <正> 1 前言以CNDO 法为基础建立的键函数方法,把量子化学的成键强度与传统的成键和非成键相互作用的有关项直接联系了起来.它对σ、π体系都能作定量描述,并且有旋转不变性,满足对称性要求,能很好地随键长变化反映键强度情况,并作了很好的尝试.按照同样原理,本文用理论上已作了许多改进的MNDO 法建立原子对作用能E_AB来量度成键强度.理论上可以证明,MNDO 法的原子更多还原

【Abstract】 It has been proposed that in LCAO-MO theory the contribution of the interactionbetween atom A and B to the total molecular energy,E_AB,may be considered asa measure of the bonding situation.E_AB is known as atom-pair interaction energy.In this paper,the proposition is examined by MNDO calculation.The E_ABvalue ofbonding atoms is negative(E_AB<-0.10eV)and of non-bonding atoms is positive orsmall negative(about E_AB>-0.10eV).When there is single,double,or triplebond between atoms of the second period,the value of E_AB is about -15,-25,-35eV respectively.For the bond between hydrogen and second period atom E_ABisabout-13 eV.The bond strength in organic molecules,the acid catalyzed dehydra-tion of alcohol,the conjugation system and the freqency displacement of carbonylgroup can be explained by the value of E_AB.Correlations are obtained by comparingE_CH for C—H bond in many simple organic molecules with their isolated strechingvibrational freqencies,v_CH,dissociation energies D°₂₉₈,and in situ bond energes,E_b.更多还原