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	hartrees
Energy at 0K	-153.026074
Energy at 298.15K	-153.025201
HF Energy	-152.505039
Nuclear repulsion energy	75.912497

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3477	3294	0.00
2	Σ_g	2282	2162	0.00
3	Σ_g	891	844	0.00
4	Σ_u	3477	3294	154.99
5	Σ_u	2088	1978	0.01
6	Π_g	636	603	0.00
6	Π_g	636	603	0.00
7	Π_g	500	473	0.00
7	Π_g	500	473	0.00
8	Π_u	633	600	75.74
8	Π_u	633	600	75.74
9	Π_u	228	216	5.23
9	Π_u	228	216	5.23

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.699
C2	0.000	0.000	-0.699
C3	0.000	0.000	1.925
C4	0.000	0.000	-1.925
H5	0.000	0.000	3.003
H6	0.000	0.000	-3.003

	C1	C2	C3	C4	H5	H6
C1		1.3986	1.2258	2.6243	2.3034	3.7019
C2	1.3986		2.6243	1.2258	3.7019	2.3034
C3	1.2258	2.6243		3.8501	1.0776	4.9277
C4	2.6243	1.2258	3.8501		4.9277	1.0776
H5	2.3034	3.7019	1.0776	4.9277		6.0053
H6	3.7019	2.3034	4.9277	1.0776	6.0053

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: CCSD/cc-pVDZ

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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All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: CCSD/cc-pVDZ

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)