Computational Chemistry

Table 6.1

Errors in AM1, PM3, and MP2(fc)/6–31G* bond lengths and angles, from Fig.

6.2

. Errors are given as AM1/PM3/MP2. In some cases (e.g. MeOH)

errors for two bonds are given, on one line and on the line below. A minus sign means that the calculated value is less than the experimental. The numbers o

f

positive, negative, and zero deviations from experiment are summarized at the bottom of each column. The averages at the bottom of each column arearithmetic means of the absolute values of the errorsa"

aexp

Bond length errors,

r"

rexp

,A

̊

Bond angle errors

C–H

O–H, N–H, S–H

C–C

C–O, N, F, Cl, S

Angles

MeOH

H

O 2

Me

CO 2

MeOH

H

O (HOH) 2

0.025/0.000/

"

0.004

0.003/

"

0.007/0.011

"

0.011/

"

0.002/0.006

0.001/

"

0.014/0.007

"

0.9/3.2/

"

0.6

0.025/0.003/0.003HCHO

H

O 2

2

CH

CH 3

3

HCHO

H

O 2

2

(HOO)

"

0.005/

"

0.024/

"

0.012

0.016/

"

0.020/0.011

"

0.031/

"

0.027/

"

0.005

0.019/

"

0.006/0.013

4.4/

"

3.5/

"

1.4

MeF

MeOH

CH

CH 2

2

MeF

MeOH (HCO)

0.021/

"

0.008/

"

0.008

0.001/

"

0.014/0.007

"

0.013/

"

0.017/

"

0.002

"

0.008/

"

0.032/0.009

"

2.2/

"

2.7/

"

0.9

(COH)"

0.2/

"

0.5/

"

0.6

HCN

HOF

HCCH

HCN

HCHO (HCH)

0.004/0.006/0.004

0.005/

"

0.020/0.013

"

0.008/

"

0.013/0.015

0.007/0.003/0.024

"

1.0/

"

0.1/

"

0.9

MeNH

2

MeNH

2

CH

CH 3

CH 2

3

MeNH

2

MeF (HCH)

0.021/0.002/0.001

"

0.010/

"

0.011/0.008

"

0.019/

"

0.014/0.000

"

0.039/

"

0.002/

"

0.006

"

1.1/

"

0.3/

"

0.8

0.023/

"

0.001/

"

0.007

CH

CH 3

3

HOCl

CH

CHCH 2

3

Me

CO 2

HOF (HOF)

0.021/0.002/

"

0.003

"

0.014/

"

0.028/0.004

"

0.027/

"

0.021/

"

0.002

0.013/

"

0.006/0.006

7.1/2.6/0.4

0.013/0.010/0.020

CH

CH 2

2

H

S 2

HCCCH

3

MeCl

MeNH

2

(HCN)

0.013/0.001/0.000

"

0.013/

"

0.046/0.004

"

0.032/

"

0.026/0.004

"

0.040/

"

0.016/

"

0.002

0.4/0.8/1.5

"

0.009/

"

0.014/0.014

CHCH

MeSH

MeSH

Me

CO (CCC) 2

0.000/0.003/0.005

"

0.015/

"

0.030/0.005

"

0.065/

"

0.018/

"

0.003

"

1.8/

"

1.8/

"

0.8

MeCl

Me

SO 2

CH

CH 3

(HCH) 3

0.015/

"

0.002/

"

0.007

"

0.060/0.019/0.010

0.4/

"

0.6/

"

0.1

MeSH

CH

CH 2

(HCH) 2

0.024/0.006/0.000

"

3.2/

"

4.0/

"

1.2

(continued

)

6.3 Applications of Semiempirical Methods 415