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State	Conformation	minimum conformation	conformer description	state description
1	1	no	D*H	¹Σ_g
1	2	yes	C2H	¹A_G

	hartrees
Energy at 0K	-152.030714
Energy at 298.15K
HF Energy	-151.649352
Nuclear repulsion energy	76.291942

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3424	3318	0.00
2	Σ_g	2257	2187	0.00
3	Σ_g	861	834	0.00
4	Σ_u	3423	3318	109.65
5	Σ_u	2061	1997	0.09
6	Π_g	587	569	0.00
6	Π_g	587	569	0.00
7	Π_g	662i	641i	0.00
7	Π_g	662i	641i	0.00
8	Π_u	555	538	97.92
8	Π_u	555	538	97.92
9	Π_u	134	130	1.40
9	Π_u	134	130	1.40

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.695
C2	0.000	0.000	-0.695
C3	0.000	0.000	1.916
C4	0.000	0.000	-1.916
H5	0.000	0.000	2.985
H6	0.000	0.000	-2.985

	C1	C2	C3	C4	H5	H6
C1		1.3907	1.2208	2.6115	2.2898	3.6805
C2	1.3907		2.6115	1.2208	3.6805	2.2898
C3	1.2208	2.6115		3.8323	1.0690	4.9013
C4	2.6115	1.2208	3.8323		4.9013	1.0690
H5	2.2898	3.6805	1.0690	4.9013		5.9703
H6	3.6805	2.2898	4.9013	1.0690	5.9703

All results from a given calculation for C₄H₂ (Diacetylene)

using model chemistry: QCISD/3-21G

States and conformations

Conformer 1 (D*H)

Conformer 2 (C2H)

	Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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You are here: Calculated > Energy > Optimized > Energy

	hartrees
Energy at 0K	-152.031199
Energy at 298.15K	-152.030104
HF Energy	-151.648025
Nuclear repulsion energy	76.336901

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3430	3324	0.00
2	A_g	2259	2189	0.00
3	A_g	870	843	0.00
4	A_g	728	705	0.00
5	A_g	572	554	0.00
6	A_u	622	603	92.54
7	A_u	186	181	4.25
8	B_g	624	605	0.00
9	B_u	3429	3324	106.90
10	B_u	2065	2001	0.08
11	B_u	666	646	89.09
12	B_u	202	196	6.54

Atom	x (Å)	y (Å)
C1	-0.034	0.694
C2	0.034	-0.694
C3	0.034	1.913
C4	-0.034	-1.913
H5	0.011	2.981
H6	-0.011	-2.981

	C1	C2	C3	C4	H5	H6
C1		1.3898	1.2209	2.6072	2.2879	3.6756
C2	1.3898		2.6072	1.2209	3.6756	2.2879
C3	1.2209	2.6072		3.8269	1.0686	4.8949
C4	2.6072	1.2209	3.8269		4.8949	1.0686
H5	2.2879	3.6756	1.0686	4.8949		5.9630
H6	3.6756	2.2879	4.8949	1.0686	5.9630

atom1	atom2	atom3	angle		atom1	atom2	atom3	angle
C1	C2	C4	180.000		C1	C3	H5	180.000
C2	C1	C3	180.000		C2	C4	H6	180.000

atom1	atom2	atom3	angle		atom1	atom2	atom3	angle
C1	C2	C4	174.069		C1	C3	H5	175.651
C2	C1	C3	174.069		C2	C4	H6	175.651

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: QCISD/3-21G

States and conformations

Conformer 1 (D*H)

Conformer 2 (C2H)

All results from a given calculation for C₄H₂ (Diacetylene)