酒精(ethanol)分子的鍵長鍵角分析
使用HF/MP2/APFD/M062X/CCSD方法搭配6-311+G(d,p)基底函數分析酒精分子的鍵長以及鍵角。
以上是NIST的實驗酒精結構
計算結果(OPT)如下:
鍵長 |
HF |
MP2 |
APFD |
M062X |
CCSD |
實驗值 |
C1C2 |
1.514 |
1.516 |
1.513 |
1.514 |
1.520 |
1.512 |
C1H5 |
1.087 |
1.094 |
1.094 |
1.092 |
1.096 |
1.098 |
C1H6 |
1.085 |
1.093 |
1.093 |
1.091 |
1.095 |
1.088 |
C1H7 |
1.085 |
1.093 |
1.093 |
1.091 |
1.095 |
1.088 |
C2H8 |
1.089 |
1.098 |
1.101 |
1.097 |
1.100 |
1.086 |
C2H9 |
1.089 |
1.098 |
1.101 |
1.097 |
1.100 |
1.086 |
C2O3 |
1.405 |
1.427 |
1.420 |
1.420 |
1.425 |
1.431 |
O3H4 |
0.940 |
0.961 |
0.959 |
0.959 |
0.958 |
0.971 |
鍵角 |
HF |
MP2 |
APFD |
M062X |
CCSD |
實驗值 |
C1C2O3 |
108.381 |
107.549 |
107.822 |
107.567 |
107.794 |
107.800 |
H5C1C2 |
110.384 |
110.352 |
110.710 |
110.634 |
110.329 |
107.810 |
H6C1C2 |
110.467 |
110.167 |
110.524 |
110.155 |
110.219 |
107.820 |
C1C2H8 |
110.079 |
110.080 |
110.090 |
110.163 |
110.051 |
111.999 |
H8C2O3 |
110.301 |
110.504 |
110.667 |
110.486 |
110.459 |
107.830 |
C2O3H4 |
110.206 |
107.573 |
108.855 |
109.098 |
107.834 |
105.400 |
鍵長的單位為埃(Ångström),鍵角為度(degrees)。
以下為鍵長以及鍵角的誤差
鍵長誤差 |
HF |
MP2 |
APFD |
M062X |
CCSD |
C1C2 |
0.002 |
0.004 |
0.001 |
0.002 |
0.008 |
C1H5 |
-0.011 |
-0.004 |
-0.004 |
-0.006 |
-0.002 |
C1H6 |
-0.003 |
0.005 |
0.005 |
0.003 |
0.007 |
C1H7 |
-0.003 |
0.005 |
0.005 |
0.003 |
0.007 |
C2H8 |
0.003 |
0.012 |
0.015 |
0.011 |
0.014 |
C2H9 |
0.003 |
0.012 |
0.015 |
0.011 |
0.014 |
C2O3 |
-0.026 |
-0.004 |
-0.011 |
-0.011 |
-0.006 |
O3H4 |
-0.031 |
-0.010 |
-0.012 |
-0.012 |
-0.013 |
平均誤差 |
-0.008 |
0.002 |
0.002 |
0.000 |
0.004 |
鍵角誤差 |
HF |
MP2 |
APFD |
M062X |
CCSD |
C1C2O3 |
0.581 |
-0.251 |
0.022 |
-0.233 |
-0.006 |
H5C1C2 |
2.574 |
2.542 |
2.900 |
2.824 |
2.519 |
H6C1C2 |
2.647 |
2.347 |
2.704 |
2.335 |
2.399 |
C1C2H8 |
-1.920 |
-1.919 |
-1.909 |
-1.836 |
-1.948 |
H8C2O3 |
2.471 |
2.674 |
2.837 |
2.656 |
2.629 |
C2O3H4 |
4.806 |
2.173 |
3.455 |
3.698 |
2.434 |
以下是鍵長的絕對誤差
絕對鍵長誤差 |
HF |
MP2 |
APFD |
M062X |
CCSD |
C1C2 |
0.002 |
0.004 |
0.001 |
0.002 |
0.008 |
C1H5 |
0.011 |
0.004 |
0.004 |
0.006 |
0.002 |
C1H6 |
0.003 |
0.005 |
0.005 |
0.003 |
0.007 |
C1H7 |
0.003 |
0.005 |
0.005 |
0.003 |
0.007 |
C2H8 |
0.003 |
0.012 |
0.015 |
0.011 |
0.014 |
C2H9 |
0.003 |
0.012 |
0.015 |
0.011 |
0.014 |
C2O3 |
0.026 |
0.004 |
0.011 |
0.011 |
0.006 |
O3H4 |
0.031 |
0.010 |
0.012 |
0.012 |
0.013 |
平均絕對誤差 |
0.010 |
0.007 |
0.008 |
0.007 |
0.009 |
以上為我嘗試模擬酒精分子間氫鍵,使用兩個酒精分子做OPT的結構圖(input file)
參考自:
http://www.rise.duke.edu/apep/pages/page.html?040402
計算結果:
第一個是自己的H原子接在另一個分的的O上(取名HO分子)的鍵長鍵角:
雙分子HO鍵長 |
MP2 |
APFD |
M062X |
實驗值 |
C1C2 |
1.524 |
1.524 |
1.522 |
1.512 |
C1H5 |
1.095 |
1.095 |
1.093 |
1.098 |
C1H6 |
1.094 |
1.095 |
1.094 |
1.088 |
C1H7 |
1.093 |
1.094 |
1.092 |
1.088 |
C2H8 |
1.093 |
1.094 |
1.092 |
1.086 |
C2H9 |
1.101 |
1.103 |
1.100 |
1.086 |
C2O3 |
1.418 |
1.410 |
1.411 |
1.431 |
O3H4 |
0.968 |
0.969 |
0.967 |
0.971 |
鍵角 |
MP2 |
APFD |
M062X |
實驗值 |
C1C2O3 |
112.648 |
113.437 |
113.437 |
107.800 |
H5C1C2 |
110.770 |
110.993 |
110.959 |
107.810 |
H6C1C2 |
110.640 |
110.502 |
110.668 |
107.820 |
C1C2H8 |
110.009 |
109.881 |
109.867 |
111.999 |
H8C2O3 |
106.075 |
106.096 |
106.229 |
107.830 |
C2O3H4 |
106.644 |
107.850 |
107.924 |
105.400 |
另一個則是O接在另一個分子的H上(OH分子):
雙分子OH鍵長 |
MP2 |
APFD |
M062X |
實驗值 |
C1C2 |
1.515 |
1.513 |
1.514 |
1.512 |
C1H5 |
1.094 |
1.094 |
1.092 |
1.098 |
C1H6 |
1.092 |
1.093 |
1.092 |
1.088 |
C1H7 |
1.092 |
1.093 |
1.091 |
1.088 |
C2H8 |
1.096 |
1.098 |
1.095 |
1.086 |
C2H9 |
1.097 |
1.099 |
1.097 |
1.086 |
C2O3 |
1.436 |
1.429 |
1.429 |
1.431 |
O3H4 |
0.962 |
0.960 |
0.960 |
0.971 |
鍵角 |
MP2 |
APFD |
M062X |
實驗值 |
C1C2O3 |
107.690 |
107.924 |
107.557 |
107.800 |
H5C1C2 |
109.991 |
110.347 |
110.372 |
107.810 |
H6C1C2 |
110.568 |
110.525 |
110.102 |
107.820 |
C1C2H8 |
110.373 |
110.624 |
110.736 |
111.999 |
H8C2O3 |
109.835 |
109.930 |
109.985 |
107.830 |
C2O3H4 |
108.256 |
109.568 |
109.833 |
105.400 |
以下為HO的誤差:
雙分子鍵長誤差HO |
MP2 |
APFD |
M062X |
C1C2 |
0.0118 |
0.0118 |
0.0103 |
C1H5 |
-0.0027 |
-0.0027 |
-0.0051 |
C1H6 |
0.0062 |
0.0073 |
0.0057 |
C1H7 |
0.0050 |
0.0056 |
0.0036 |
C2H8 |
0.0072 |
0.0084 |
0.0059 |
C2H9 |
0.0149 |
0.0172 |
0.0142 |
C2O3 |
-0.0134 |
-0.0214 |
-0.0201 |
O3H4 |
-0.0032 |
-0.0019 |
-0.0039 |
平均誤差 |
0.0032 |
0.0030 |
0.0013 |
鍵角誤差 |
MP2 |
APFD |
M062X |
C1C2O3 |
4.848 |
5.637 |
5.637 |
H5C1C2 |
2.960 |
3.183 |
3.149 |
H6C1C2 |
2.820 |
2.682 |
2.848 |
C1C2H8 |
-1.990 |
-2.118 |
-2.132 |
H8C2O3 |
-1.755 |
-1.734 |
-1.601 |
C2O3H4 |
1.244 |
2.450 |
2.524 |
HO的特徵是,計算C1C2O3鍵角時有巨大的誤差,不過C2O3H4的鍵角的誤差只有單分子的60%左右。
鍵長方面的結果與單分子酒精相去不遠。
絕對鍵長誤差HO |
MP2 |
APFD |
M062X |
C1C2 |
0.0118 |
0.0118 |
0.0103 |
C1H5 |
0.0027 |
0.0027 |
0.0051 |
C1H6 |
0.0062 |
0.0073 |
0.0057 |
C1H7 |
0.0050 |
0.0056 |
0.0036 |
C2H8 |
0.0072 |
0.0084 |
0.0059 |
C2H9 |
0.0149 |
0.0172 |
0.0142 |
C2O3 |
0.0134 |
0.0214 |
0.0201 |
O3H4 |
0.0032 |
0.0019 |
0.0039 |
平均絕對誤差 |
0.0081 |
0.0095 |
0.0086 |
以下為OH的誤差:
雙分子鍵長誤差OH |
MP2 |
APFD |
M062X |
C1C2 |
0.0035 |
0.0006 |
0.0023 |
C1H5 |
-0.0043 |
-0.0044 |
-0.0065 |
C1H6 |
0.0044 |
0.0050 |
0.0041 |
C1H7 |
0.0044 |
0.0051 |
0.0031 |
C2H8 |
0.0101 |
0.0117 |
0.0089 |
C2H9 |
0.0113 |
0.0132 |
0.0112 |
C2O3 |
0.0046 |
-0.0021 |
-0.0024 |
O3H4 |
-0.0094 |
-0.0112 |
-0.0108 |
平均誤差 |
0.0031 |
0.0022 |
0.0012 |
鍵角誤差 |
MP2 |
APFD |
M062X |
C1C2O3 |
-0.110 |
0.124 |
-0.243 |
H5C1C2 |
2.181 |
2.537 |
2.562 |
H6C1C2 |
2.748 |
2.705 |
2.282 |
C1C2H8 |
-1.626 |
-1.375 |
-1.263 |
H8C2O3 |
2.005 |
2.100 |
2.155 |
C2O3H4 |
2.856 |
4.168 |
4.433 |
OH的特徵是,鍵長的平均絕對誤差比單分子酒精還要小一點點。
在鍵角方面則沒有巨大的差異。
絕對鍵長誤差OH |
MP2 |
APFD |
M062X |
C1C2 |
0.0035 |
0.0006 |
0.0023 |
C1H5 |
0.0043 |
0.0044 |
0.0065 |
C1H6 |
0.0044 |
0.0050 |
0.0041 |
C1H7 |
0.0044 |
0.0051 |
0.0031 |
C2H8 |
0.0101 |
0.0117 |
0.0089 |
C2H9 |
0.0113 |
0.0132 |
0.0112 |
C2O3 |
0.0046 |
0.0021 |
0.0024 |
O3H4 |
0.0094 |
0.0112 |
0.0108 |
平均絕對誤差 |
0.0065 |
0.0066 |
0.0062 |
以上為我用了三個酒精分子做OPT的結構圖
由於這個計算量非常龐大,因此我只有做MP2搭配6-31+G(d,p)的OPT計算
我取的分子是中間的分子,為受到兩個氫鍵影響的分子
計算結果:
三分子鍵長 |
MP2 |
實驗值 |
C1C2 |
1.513 |
1.512 |
C1H5 |
1.090 |
1.098 |
C1H6 |
1.089 |
1.088 |
C1H7 |
1.089 |
1.088 |
C2H8 |
1.094 |
1.086 |
C2H9 |
1.094 |
1.086 |
C2O3 |
1.434 |
1.431 |
O3H4 |
0.980 |
0.971 |
鍵角 |
MP2 |
實驗值 |
C1C2O3 |
107.828 |
107.800 |
H5C1C2 |
110.449 |
107.810 |
H6C1C2 |
110.012 |
107.820 |
C1C2H8 |
110.676 |
111.999 |
H8C2O3 |
109.604 |
107.830 |
C2O3H4 |
109.338 |
105.400 |
與實驗值的誤差為:
三分子鍵長誤差 |
MP2 |
C1C2 |
0.0008 |
C1H5 |
-0.0077 |
C1H6 |
0.0014 |
C1H7 |
0.0015 |
C2H8 |
0.0077 |
C2H9 |
0.0081 |
C2O3 |
0.0031 |
O3H4 |
0.0085 |
平均誤差 |
0.0029 |
鍵角誤差 |
MP2 |
C1C2O3 |
0.028 |
H5C1C2 |
2.639 |
H6C1C2 |
2.192 |
C1C2H8 |
-1.323 |
H8C2O3 |
1.774 |
C2O3H4 |
3.938 |
三分子絕對誤差 |
MP2 |
C1C2 |
0.0008 |
C1H5 |
0.0077 |
C1H6 |
0.0014 |
C1H7 |
0.0015 |
C2H8 |
0.0077 |
C2H9 |
0.0081 |
C2O3 |
0.0031 |
O3H4 |
0.0085 |
平均絕對誤差 |
0.0048 |
有兩個氫鍵的酒精分子在鍵長方面有很卓越的計算結果,但遺憾的是在鍵角依然沒有起色。
結論:
1.
考慮氫鍵之後,計算鍵長的結果有變得更好(有一個氫鍵的酒精分子不明顯,但是兩個氫鍵則變好很多),但是鍵角並沒有明顯差異。
2.
除了HF方法之外,其餘方法在鍵長方面都算得精準(差異在0.01~0.02埃以內)。
3.
在鍵角方面為MP2以及CCSD綜合起來算得最好。