吳奕霆-第十週作業

20221115 計算化學第十週作業

611260037 吳奕霆

  1. Calculate the structures and atomization energies (AE) of following molecules with following methods then compare with the experimental values.

molecule ：H2、Li2、B2、C2、N2、O2、F2、P2、S2、Cl2

method：

MP2/6-31+G(d,p)

B3LYP/aug-cc-pVTZ

 

 

Experimental value is from :

https://lab409chem.ccu.edu.tw/var/file/80/1080/img/866/AtomizationEnergies.pdf

 

 

MP2/6-31+G(d,p)

分子

AE(kcal/mol)

Experimental Value(kcal/mol)

誤差

H2

101.15

109.48

8.33

Li2

14.33

24.6

10.27

B2

38.97

67.14

28.17

C2

237.05

145.73

91.32

N2

373.35

228.46

144.90

O2

223.36

119.99

103.37

F2

34.77

38.2

3.42

P2

199.84

117.09

82.75

S2

153.06

101.67

51.39

Cl2

41.94

57.97

16.02

MAE : 54.00

1

2

 

 

B3LYP/aug-cc-pVTZ

分子

AE(kcal/mol)

Experimental Value(kcal/mol)

誤差

H2

110.13

109.48

0.65

Li2

20.90

24.6

3.70

B2

39.19

67.14

27.95

C2

200.72

145.73

54.99

N2

355.01

228.46

126.55

O2

211.56

119.99

91.56

F2

37.12

38.2

1.08

P2

189.60

117.09

72.51

S2

155.13

101.67

53.46

Cl2

54.018

57.97

3.95

MAE : 43.64

3

4

Conclusion :

  1. 較大的基底函數組合(B3LYP/aug-cc-pVTZ)，誤差較小
  2. N2,O2兩者明顯誤差較大，但同族不同週期的P2, S2誤差則較小

 

 

 

  1. Calculate the standard enthalpy of formation (ΔH°f) of AHn (A = H~Ne) with following methods then compare with the experimental values.

optimization：MP2/aug-cc-pVTZ

single point energy：CCSD(T)/aug-cc-pVTZ

 

 

Experimental value is from :

https://cccbdb.nist.gov/xp1x.asp?prop=1

 

 

Formula about enthalpy of formation :

 

Where R=0.00198 kcal/mol‧K，T=298.15 K

 

 

MP2/aug-cc-pVTZ (Optimize + frequency)

分子

ΔH°f (kcal/mol)

Experimental value(kcal/mol)

Error(kcal/mol)

H2

5.97

0

5.97

LiH

38.94

33.61

5.33

BH3

36.26

21.03

15.23

CH4

-52.21

-17.83

34.38

NH3

-78.04

-10.98

67.06

H2O

-123.2

-57.79

65.41

HF

-67.61

-65.32

2.29

MAE : 27.95

5

3

 

 

CCSD(T)/aug-cc-pVTZ (Only frequency)

分子

ΔH°f (kcal/mol)

Experimental value(kcal/mol)

Error(kcal/mol)

H2

9.11

0

9.11

LiH

34.25

33.61

0.64

BH3

41.04

21.03

20.01

CH4

-44.15

-17.83

26.32

NH3

-63.73

-10.98

52.75

H2O

-98.38

-57.79

40.59

HF

-57.91

-65.32

7.40

MAE : 22.41

5

6

 

Conclusion :

  1. 高階理論的誤差較小，但CCSD(T)無法算出Be的Thermal correction to energy
  2. NH3，H2O的誤差較大