自然电子轨道NBO分析方法.doc

自然键轨道(NBO)分析方法 分子轨道未经定域化处理，将导致计算结果与我们通常的成键概念有所不同。例如在乙烯分子中，碳碳之间为双键，但在正则MO中，反映C与C之间成键作用的MO可能有多个，因此根据正则MO的结果，我们无法断定C—C是单键还是双键。此时，通过对正则MO的定域化处理，可以得到通常意义上的成键图像。 正则MO的定域化处理方法较多，其中较为常用的是NBO方法，其使用方法是在输入文件中添加关键词：POP=NBO 以乙烯分子为例： %mem=32mb #p b3lyp/3-21g pop=nbo 进行NBO成键分析 The NBO analysis of ethylene 0,1 C C,1,CC H,1,CH,2,HCC H,1,CH,2,HCC,3,180.,0 H,2,CH,1,HCC,3,180.,0 H,2,CH,1,HCC,4,180.,0 CC=1.31477 CH=1.07363 HCC=121.8867 Entering Link 1 = C:\G03W\l1.exe PID= 2100. Copyright (c) 1988,1990,1992,1993,1995,1998,2003, Gaussian, Inc. All Rights Reserved. This is the Gaussian(R) 03 program. It is based on the the Gaussian(R) 98 system (copyright 1998, Gaussian, Inc.), the Gaussian(R) 94 system (copyright 1995, Gaussian, Inc.), the Gaussian 92(TM) system (copyright 1992, Gaussian, Inc.), the Gaussian 90(TM) system (copyright 1990, Gaussian, Inc.), the Gaussian 88(TM) system (copyright 1988, Gaussian, Inc.), the Gaussian 86(TM) system (copyright 1986, Carnegie Mellon University), and the Gaussian 82(TM) system (copyright 1983, Carnegie Mellon University). Gaussian is a federally registered trademark of Gaussian, Inc. This software contains proprietary and confidential information, including trade secrets, belonging to Gaussian, Inc. This software is provided under written license and may be used, copied, transmitted, or stored only in accord with that written license. The following legend is applicable only to US Government contracts under DFARS: RESTRICTED RIGHTS LEGEND Use, duplication or disclosure by the US Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013. Gaussian, Inc. Carnegie Office Park, Building 6, Pittsburgh, PA 15106 USA The following legend is applicable only to US Government contracts under FAR: RESTRICTED RIGHTS LEGE