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本文提出在LCAO-MO法中,可用A原子与B原子的双原子作用能对分子总能量贡献的负值,IZAB,作为成键情况的度量,称为键级函数。并以CNDO/2方法对一些典型化合物进行了计算。不成键的原子间的|Y_(AB)|<0.021(A.U.),当第二周期原子间成单、双、叁键时,Y_(AB)分别为1.0,1.7,2.3A.U.左右。而氢与第二周期原子成键时,Y_(AB)约0.75A.U.。这样,就可在分子轨道理论中给出了价键图象,并在键级函数的基础上定义了价数和饱和值。用键级函数可以解释烷、烯、炔中的碳氢键强度、共轭作用、醇的酸催化脱水及羰基频率位移等现象。
In this paper, we propose that in the LCAO-MO method, the negative contribution of the diatomic contribution of A atoms to B atoms to the total energy of a molecule, IZAB, is a measure of the bond formation and is called a bond-level function. Some typical compounds were calculated by CNDO / 2 method. Y_ (AB) | <0.021 (A.U.), which are not bond atoms, Y_ (AB) are 1.0, 1.7 and 2.3A.U. respectively when the second period atoms are single, double and triple bonds. When the hydrogen bonds with the second periodic atom, Y_ (AB) is about 0.75A.U. In this way, valence bond images can be given in molecular orbital theory, and valence and saturation values can be defined on the basis of bond-level functions. Key-level functions can be used to explain the carbon-hydrogen bond strength, the conjugation, the acid-catalyzed dehydration of alcohols and the carbonyl frequency shift in alkanes, alkenes and alkynes.