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	hartrees
Energy at 0K	-152.456706
Energy at 298.15K	-152.456080
HF Energy	-152.456706
Nuclear repulsion energy	77.243062

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3505	3364	0.00
2	Σ_g	2337	2243	0.00
3	Σ_g	925	888	0.00
4	Σ_u	3505	3365	168.10
5	Σ_u	2140	2054	0.04
6	Π_g	733	703	0.00
6	Π_g	733	703	0.00
7	Π_g	555	532	0.00
7	Π_g	555	532	0.00
8	Π_u	727	698	107.71
8	Π_u	727	698	107.71
9	Π_u	227	218	9.03
9	Π_u	227	218	9.03

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.680
C2	0.000	0.000	-0.680
C3	0.000	0.000	1.891
C4	0.000	0.000	-1.891
H5	0.000	0.000	2.954
H6	0.000	0.000	-2.954

	C1	C2	C3	C4	H5	H6
C1		1.3609	1.2105	2.5714	2.2733	3.6343
C2	1.3609		2.5714	1.2105	3.6343	2.2733
C3	1.2105	2.5714		3.7819	1.0629	4.8448
C4	2.5714	1.2105	3.7819		4.8448	1.0629
H5	2.2733	3.6343	1.0629	4.8448		5.9076
H6	3.6343	2.2733	4.8448	1.0629	5.9076

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: HSEh1PBE/3-21G*

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	-0.044
2	C	-0.044
3	C	-0.272
4	C	-0.272
5	H	0.316
6	H	0.316

<r²>	78.403
(<r²>)^1/2	8.855

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: HSEh1PBE/3-21G*

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)