The property of chemical bonds in boron hydride molecule has always been attached to great importance by experimental or theoretical chemists. So far, the prevalent theory was LonguetHiggins’ bridge three-center two-...The property of chemical bonds in boron hydride molecule has always been attached to great importance by experimental or theoretical chemists. So far, the prevalent theory was LonguetHiggins’ bridge three-center two-electron bond, which was developed later by Lipscomb as the styx rules of boron hydride.展开更多
本文用LCAO-MO-SCF ab initio方法,对OH^-+CH_3F→CH_3OH+F^-反应进行了过渡态理论及前线轨道理论的量子化学研究。以4-31G为基组,计算了反应进程的势能曲线,得到了过渡态的几何构型,并用MP2方法进行了电子库仑相关效应的校正,反应潘化...本文用LCAO-MO-SCF ab initio方法,对OH^-+CH_3F→CH_3OH+F^-反应进行了过渡态理论及前线轨道理论的量子化学研究。以4-31G为基组,计算了反应进程的势能曲线,得到了过渡态的几何构型,并用MP2方法进行了电子库仑相关效应的校正,反应潘化能的计算值与实验数据较为一致。用前线轨道理论对反应中分子重新组合过程进行了轨道分析,较全面地解释了该反应的机理。展开更多
建立 A—B 键中某价电子的键强参数的概念:f_(1,A-B)=(?)ε_(?)/(?)ι_(A-B)表达价分子轨道 i 上一个电子对 A—B 键中化学结合力的贡献.从理论上说明它是 i-电子云对 A 及 B 核的“拉力”以及对其它电子的“推力”的“净效应”大小.就 ...建立 A—B 键中某价电子的键强参数的概念:f_(1,A-B)=(?)ε_(?)/(?)ι_(A-B)表达价分子轨道 i 上一个电子对 A—B 键中化学结合力的贡献.从理论上说明它是 i-电子云对 A 及 B 核的“拉力”以及对其它电子的“推力”的“净效应”大小.就 CO,N_2,O_2说明其所反映的“成键性质”与 UPS 的实验数据相一致.就几个均匀环状化合物证明其有很好的“加和性”.多中心键的 F_1与其中“双中心”键的 f_1之和相等.其所反映的“成键”性质与 MO 的对称性及电荷密度分布图的定性结论完全一致.f_(▲_B)=(?)所反映的键强度与键长及“键电荷”的大小顺序相适应.展开更多
Although 'ab initio' quantum chemical calculation is theoretically very important, and has many practical uses, yet due to the fact that the amount of calculation work is nearly proportional to the 4th power o...Although 'ab initio' quantum chemical calculation is theoretically very important, and has many practical uses, yet due to the fact that the amount of calculation work is nearly proportional to the 4th power of the number of the basis functions used, the calculation work of even a medium-type molecule such as benzene, is already enormous. So it is very difficult to extend its use.展开更多
文摘The property of chemical bonds in boron hydride molecule has always been attached to great importance by experimental or theoretical chemists. So far, the prevalent theory was LonguetHiggins’ bridge three-center two-electron bond, which was developed later by Lipscomb as the styx rules of boron hydride.
文摘本文用LCAO-MO-SCF ab initio方法,对OH^-+CH_3F→CH_3OH+F^-反应进行了过渡态理论及前线轨道理论的量子化学研究。以4-31G为基组,计算了反应进程的势能曲线,得到了过渡态的几何构型,并用MP2方法进行了电子库仑相关效应的校正,反应潘化能的计算值与实验数据较为一致。用前线轨道理论对反应中分子重新组合过程进行了轨道分析,较全面地解释了该反应的机理。
文摘建立 A—B 键中某价电子的键强参数的概念:f_(1,A-B)=(?)ε_(?)/(?)ι_(A-B)表达价分子轨道 i 上一个电子对 A—B 键中化学结合力的贡献.从理论上说明它是 i-电子云对 A 及 B 核的“拉力”以及对其它电子的“推力”的“净效应”大小.就 CO,N_2,O_2说明其所反映的“成键性质”与 UPS 的实验数据相一致.就几个均匀环状化合物证明其有很好的“加和性”.多中心键的 F_1与其中“双中心”键的 f_1之和相等.其所反映的“成键”性质与 MO 的对称性及电荷密度分布图的定性结论完全一致.f_(▲_B)=(?)所反映的键强度与键长及“键电荷”的大小顺序相适应.
文摘Although 'ab initio' quantum chemical calculation is theoretically very important, and has many practical uses, yet due to the fact that the amount of calculation work is nearly proportional to the 4th power of the number of the basis functions used, the calculation work of even a medium-type molecule such as benzene, is already enormous. So it is very difficult to extend its use.
