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	hartrees
Energy at 0K	-152.571753
Energy at 298.15K	-152.571106
HF Energy	-152.571753
Nuclear repulsion energy	77.167138

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	Σ_g	3493	3358	0.00
2	Σ_g	2320	2230	0.00
3	Σ_g	919	883	0.00
4	Σ_u	3494	3359	164.76
5	Σ_u	2127	2044	0.10
6	Π_g	721	693	0.00
6	Π_g	721	693	0.00
7	Π_g	549	528	0.00
7	Π_g	549	528	0.00
8	Π_u	716	688	108.68
8	Π_u	716	688	108.68
9	Π_u	226	217	8.68
9	Π_u	226	217	8.68

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.000	0.681
C2	0.000	0.000	-0.681
C3	0.000	0.000	1.893
C4	0.000	0.000	-1.893
H5	0.000	0.000	2.956
H6	0.000	0.000	-2.956

	C1	C2	C3	C4	H5	H6
C1		1.3618	1.2120	2.5738	2.2754	3.6372
C2	1.3618		2.5738	1.2120	3.6372	2.2754
C3	1.2120	2.5738		3.7858	1.0634	4.8492
C4	2.5738	1.2120	3.7858		4.8492	1.0634
H5	2.2754	3.6372	1.0634	4.8492		5.9126
H6	3.6372	2.2754	4.8492	1.0634	5.9126

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: B3PW91/3-21G

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	-0.027
2	C	-0.027
3	C	-0.287
4	C	-0.287
5	H	0.314
6	H	0.314

<r²>	78.507
(<r²>)^1/2	8.860

All results from a given calculation for C4H2 (Diacetylene)

using model chemistry: B3PW91/3-21G

States and conformations

All results from a given calculation for C₄H₂ (Diacetylene)