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	hartrees
Energy at 0K	-151.654296
Energy at 298.15K	-151.654017
HF Energy	-151.654296
Nuclear repulsion energy	77.881347

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3656	3300	0.00
2	Σ_g	2512	2267	0.00
3	Σ_g	939	848	0.00
4	Σ_u	3653	3298	172.46
5	Σ_u	2294	2071	0.00
6	Π_g	927	836	0.00
6	Π_g	927	836	0.00
7	Π_g	598	540	0.00
7	Π_g	598	540	0.00
8	Π_u	915	826	121.63
8	Π_u	915	826	121.63
9	Π_u	244	220	12.05
9	Π_u	244	220	12.05

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.687
C2	0.000	0.000	-0.687
C3	0.000	0.000	1.876
C4	0.000	0.000	-1.876
H5	0.000	0.000	2.928
H6	0.000	0.000	-2.928

	C1	C2	C3	C4	H5	H6
C1		1.3734	1.1897	2.5631	2.2409	3.6143
C2	1.3734		2.5631	1.1897	3.6143	2.2409
C3	1.1897	2.5631		3.7528	1.0512	4.8040
C4	2.5631	1.1897	3.7528		4.8040	1.0512
H5	2.2409	3.6143	1.0512	4.8040		5.8553
H6	3.6143	2.2409	4.8040	1.0512	5.8553

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: HF/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	-0.200
2	C	-0.200
3	C	-0.182
4	C	-0.182
5	H	0.382
6	H	0.382

<r²>	77.791
(<r²>)^1/2	8.820

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: HF/3-21G*

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)