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	hartrees
Energy at 0K	-152.432555
Energy at 298.15K	-152.431038
HF Energy	-152.305975
Nuclear repulsion energy	76.920657

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3499	3499	0.00
2	Σ_g	2272	2272	0.00
3	Σ_g	899	899	0.00
4	Σ_u	3499	3499	148.63
5	Σ_u	2081	2081	0.01
6	Π_g	646	646	0.00
6	Π_g	646	646	0.00
7	Π_g	223	223	0.00
7	Π_g	223	223	0.00
8	Π_u	653	653	101.48
8	Π_u	653	653	101.48
9	Π_u	204	204	5.42
9	Π_u	204	204	5.42

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.684
C2	0.000	0.000	-0.684
C3	0.000	0.000	1.900
C4	0.000	0.000	-1.900
H5	0.000	0.000	2.962
H6	0.000	0.000	-2.962

	C1	C2	C3	C4	H5	H6
C1		1.3681	1.2161	2.5842	2.2775	3.6456
C2	1.3681		2.5842	1.2161	3.6456	2.2775
C3	1.2161	2.5842		3.8003	1.0614	4.8617
C4	2.5842	1.2161	3.8003		4.8617	1.0614
H5	2.2775	3.6456	1.0614	4.8617		5.9231
H6	3.6456	2.2775	4.8617	1.0614	5.9231

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: B2PLYP/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	-0.059
2	C	-0.059
3	C	-0.238
4	C	-0.238
5	H	0.298
6	H	0.298

<r²>	79.124
(<r²>)^1/2	8.895

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: B2PLYP/3-21G*

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)