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	hartrees
Energy at 0K	-23.621861
Energy at 298.15K	-23.622119
HF Energy	-23.621861
Nuclear repulsion energy	36.563044

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3454	3366	0.00
2	Σ_g	2248	2190	0.00
3	Σ_g	891	869	0.00
4	Σ_u	3455	3367	166.20
5	Σ_u	2050	1997	3.53
6	Π_g	1559	1519	0.00
6	Π_g	1559	1519	0.00
7	Π_g	744	725	0.00
7	Π_g	744	725	0.00
8	Π_u	1000	975	185.07
8	Π_u	1000	975	185.07
9	Π_u	334	326	22.29
9	Π_u	334	326	22.29

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.692
C2	0.000	0.000	-0.692
C3	0.000	0.000	1.917
C4	0.000	0.000	-1.917
H5	0.000	0.000	2.982
H6	0.000	0.000	-2.982

	C1	C2	C3	C4	H5	H6
C1		1.3836	1.2255	2.6091	2.2907	3.6743
C2	1.3836		2.6091	1.2255	3.6743	2.2907
C3	1.2255	2.6091		3.8346	1.0652	4.8997
C4	2.6091	1.2255	3.8346		4.8997	1.0652
H5	2.2907	3.6743	1.0652	4.8997		5.9649
H6	3.6743	2.2907	4.8997	1.0652	5.9649

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

All results from a given calculation for C₄H₂ (Diacetylene)

using model chemistry: B3LYP/CEP-121G

States and conformations

	Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Number	Element	Mulliken
1	C	3.596
2	C	3.596
3	C	-3.936
4	C	-3.936
5	H	0.339
6	H	0.339

<r²>	63.685
(<r²>)^1/2	7.980

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: B3LYP/CEP-121G

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)