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	hartrees
Energy at 0K	-152.456706
Energy at 298.15K	-152.456090
HF Energy	-152.456706
Nuclear repulsion energy	77.242341

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3505	3376	0.00
2	Σ_g	2337	2251	0.00
3	Σ_g	925	891	0.00
4	Σ_u	3505	3377	168.09
5	Σ_u	2140	2062	0.04
6	Π_g	733	706	0.00
6	Π_g	733	706	0.00
7	Π_g	555	534	0.00
7	Π_g	555	534	0.00
8	Π_u	727	701	107.71
8	Π_u	727	701	107.71
9	Π_u	227	218	9.02
9	Π_u	227	218	9.02

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		1.3610	1.2105	2.5715	2.2734	3.6343
C2	1.3610		2.5715	1.2105	3.6343	2.2734
C3	1.2105	2.5715		3.7820	1.0629	4.8448
C4	2.5715	1.2105	3.7820		4.8448	1.0629
H5	2.2734	3.6343	1.0629	4.8448		5.9077
H6	3.6343	2.2734	4.8448	1.0629	5.9077

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>	78.405
(<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)