首页> 外文期刊>The Journal of Chemical Physics >THE IMOMO METHOD - INTEGRATION OF DIFFERENT LEVELS OF MOLECULAR ORBITAL APPROXIMATIONS FOR GEOMETRY OPTIMIZATION OF LARGE SYSTEMS - TEST FOR N-BUTANE CONFORMATION AND S(N)2 REACTION - RCL+CL-
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THE IMOMO METHOD - INTEGRATION OF DIFFERENT LEVELS OF MOLECULAR ORBITAL APPROXIMATIONS FOR GEOMETRY OPTIMIZATION OF LARGE SYSTEMS - TEST FOR N-BUTANE CONFORMATION AND S(N)2 REACTION - RCL+CL-

机译:IMOMO方法-整合分子轨道近似的不同层以优化大型系统的几何-N-丁烷构象和S(N)2反应的测试-RCL + CL-

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摘要

A integration of two different levels of MO approximation is presented. Only the active or more difficult part of a molecule is treated at a higher level of approximation and the rest of the molecule at a lower level of approximation. The integrated total energy and energy derivatives are defined from three different calculations, and the structure of transition state as well as the equilibrium structure can be optimized using the integrated energy. Any combination of any molecular orbital approximations (ab initio, density functional to semi-empirical) can be used. Test calculations in the IMOMO method have been performed and compared with normal MO calculations for the conformation energy of ethane and n-butane and the S(N)2 reaction of ethyl, propyl, isobutyl, and neopentyl chloride with Cl-. The results indicate that these methods have a tremendous potential for theoretical study of larger molecules, in particular for transition states. (C) 1996 American Institute of Physics. [References: 16]
机译:提出了两个不同水平的MO逼近的积分。仅以较高的近似水平处理分子的活性或较困难的部分,而以较低的近似水平处理分子的其余部分。积分的总能量和能量导数是通过三种不同的计算定义的,可以使用积分能量优化过渡态的结构以及平衡结构。可以使用任何分子轨道近似的任何组合(从头算起,对半经验的密度函数)。进行了IMOMO方法的测试计算,并将其与常规MO计算得出的乙烷和正丁烷的构象能以及乙基,丙基,异丁基和新戊基氯与Cl-的S(N)2反应进行了比较。结果表明,这些方法对于较大分子的理论研究具有巨大的潜力,特别是对于过渡态。 (C)1996年美国物理研究所。 [参考:16]

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