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amytaotao

新虫 (初入文坛)

应助: 0 (幼儿园)
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帖子: 49
在线: 21.4小时
虫号: 450842
注册: 2007-11-04
专业: 物理化学

[求助] nbo计算出来C原子有孤对电子怎么回事

用NBO计算了两个过渡态ts1a和ts1b的二级微扰相互作用，如附件中图所示，ts1a中，最稳定的二级作用是C5的孤对电子离域到N45=N44的π*轨道上，而ts1b中最稳定的二级相互作用是C6的孤对电子离域到C3=C4的π*轨道。感觉很奇怪，C原子怎么会有孤对电子呢？审稿人也对此提了疑问。下面是审稿人的一段话：When results of the NBO analysis are discussed, lone electron pairs at the C5 and C6 atoms in TS1a and TS1b are indicated. This is a bit strange, at least for experimentalists, that a carbon atom in the sp2/sp3 hybrid state has a lone electron pair. May be the NBO analysis failed to find automatically the most stable resonance structure? I recommend to repeat the NBO calculations setting manually the intuitively most stable resonance structures without the lone electron pairs at the C atoms and then to compare results. 求大家意见该怎么办才好。
我查看了NBO的手册，想用choose试试，结果不知道为啥跟不加choose一模一样，请大家帮我看看输入文件是否有误，输入文件如下：
%nprocshared=16
%nosave
%mem=12GB
%chk=ts1b.chk
# ub3lyp/6-31g(d) pop=(savenbo,nboread)

Title Card Required

0 1
C                -1.65759800 4.16030600 -1.05909800
C                -1.76849000 2.83983200 -1.21181500
C                1.25887400 0.40308300 0.90504800
C                2.37067500 0.28987600 0.14290300
C                3.96231000 0.10420300 1.14060600
*****继续原子坐标
空格行
$CHOOSE
LONE  5 45 44 END
BOND  D 5 45  D 45 44  D 6 4  D 4 3  END
NOBOND 4 5  END
$NBO BNDIDX
$END

ts1a.jpg