林昶廷-第6週作業1024

1.Please use ChatGPT to explore a thematic series of questions within the scope of computational chemistry and follow up with further inquiries about any unfamiliar terms

ChatGPT

2.Use Gaussian or WebMO to calculate the Electron Affinity of Helium、Neon、Argon, by using B3LYP、MP2 and M062X theoretical methods with cc-pVTZ、aug-cc-pVTZ、d-aug-cc-pVTZ basis set, and do some simple statistical analysis.(check your unit、analysis tools)

1.Electron Affinity of Helium、Neon、Argon(Unit:Kcal/mol)

He	B3LYP	MP2	M062	Expt
cc-pVTZ	376.8	394.5	367.5	11.53
aug-cc-pVTZ	61.9	68.3	62.7
d-aug-cc-pVTZ	10.1	13.2	10.7
NE	B3LYP	MP2	M062	Expt
cc-pVTZ	629.9	671.9	634.6	27.67
aug-cc-pVTZ	130.2	141.3	131.7
d-aug-cc-pVTZ	28.4	440.4	31.8
Ar	B3LYP	MP2	M062	Expt
cc-pVTZ	302.7	501.4	301.1	23.06
aug-cc-pVTZ	72.2	77.8	72.8

2-1.不同理論下比較基底函數的計算結果

3.誤差

ABS error(Kcal/mol)	He	NE	Ar	MAE
B3LYP/cc-pVTZ	371.78	618.94	294.73	428.48
B3LYP/aug-cc-pVTZ	56.86	119.18	64.20	80.08
B3LYP/d-aug-cc-pVTZ	5.11	17.42		11.27
MP2 /cc-pVTZ	389.47	660.87	493.41	514.58
MP2 /aug-cc-pVTZ	63.35	130.30	69.82	87.82
MP2 /d-aug-cc-pVTZ	8.18	24.64		16.41
M062X/cc-pVTZ	362.54	629.62	296.08	429.41
M062X/aug-cc-pVTZ	57.68	126.68	67.84	84.07
M062X/d-aug-cc-pVTZ	5.67	26.82		16.24

結論:雖然d-aug-cc-pVTZ算不出來導致數值空缺，但從MAE可以看出基底函數愈複雜則得到的結果愈接近真實值，

Try to add an additional set of diffuse functions for the s orbital of He, and the s and p orbitals of Ne and Ar. ( in the 6-31G basis set )

Table.Use B3LYP with 6-31G basis set (Unit:Kcal/mol)

B3lyp	He	Ne	Ar
6-31G**	143.2	1009.4	684.1
6-31+G**	71.4	36.9791	464.3
6-31++G**	37.5	29.27	464.5
Exp	11	27.7	23.6

Table.Use MP2 with 6-31G basis set (Unit:Kcal/mol)

MP2	He	Ne	Ar
6-31G**	158.6	1237.3	354.7
6-31+G**	46.3	89.3	47.6
6-31++G**	12.2	81.5	45.9
Exp	11	27.7	23.6

Table.Absolute error(Unit:Kcal/mol)

B3LYP	He	Ne	Ar
6-31G**	132.23	998.42	673.05
6-31+G**	60.35	25.98	452.99
6-31++G**	26.52	18.27	453.49
MP2	He	Ne	Ar
6-31G**	147.6	1226.3	343.69
6-31+G**	35.32	78.25	36.64
6-31++G**	1.2	70.54	34.98

結論:增加diffuse functions在趨勢上絕對誤差會愈來愈小

Try to use Gaussian or WebMO to optimize the H₃⁺ molecule and calculate the linear dissociation energy according to the formula provided in the PDF lecture.

H₂+ H₂⁺àH₃⁺+H

Energy of difference H type

CISD/aug-cc-pVTZ OPT
H type	H₃⁺	H	H₂	H₂⁺
Hartree	-1.27710	-0.49982	-1.16377	-0.53090
Kcal/mol	-801.4	-313.6	-730.3	-333.1

linear dissociation energy according to the difference formula

dissociation energy:(-801.4+-313.6)-(-730.3-333.1)= -51.6

瀏覽數:

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