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	hartrees
Energy at 0K	-24.812950
Energy at 298.15K	-24.816056
HF Energy	-24.812950
Nuclear repulsion energy	49.610322

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3229	3147	0.00
2	A_g	1573	1533	0.00
3	A_g	1107	1079	0.00
4	A_g	952	927	0.00
5	A_u	887	864	0.00
6	A_u	531	518	0.00
7	B_1g	869	847	0.00
8	B_1u	3212	3130	42.18
9	B_1u	1569	1529	8.28
10	B_1u	1055	1028	1.41
11	B_2g	642	625	0.00
12	B_2u	3188	3106	19.76
13	B_2u	1254	1222	39.69
14	B_2u	683	666	9.61
15	B_3g	3170	3089	0.00
16	B_3g	1168	1138	0.00
17	B_3g	876	853	0.00
18	B_3u	620	604	201.02

Atom	y (Å)	z (Å)
C1	0.680	0.802
C2	0.680	-0.802
C3	-0.680	0.802
C4	-0.680	-0.802
H5	1.452	1.565
H6	1.452	-1.565
H7	-1.452	1.565
H8	-1.452	-1.565

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6042	1.3601	2.1032	1.0850	2.4894	2.2642	3.1854
C2	1.6042		2.1032	1.3601	2.4894	1.0850	3.1854	2.2642
C3	1.3601	2.1032		1.6042	2.2642	3.1854	1.0850	2.4894
C4	2.1032	1.3601	1.6042		3.1854	2.2642	2.4894	1.0850
H5	1.0850	2.4894	2.2642	3.1854		3.1292	2.9038	4.2690
H6	2.4894	1.0850	3.1854	2.2642	3.1292		4.2690	2.9038
H7	2.2642	3.1854	1.0850	2.4894	2.9038	4.2690		3.1292
H8	3.1854	2.2642	2.4894	1.0850	4.2690	2.9038	3.1292

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.650
C1	C3	C4	90.000	C1	C3	H7	135.350
C2	C1	C3	90.000	C2	C1	H5	134.650
C2	C4	C3	90.000	C3	C1	H5	135.350
C4	C2	H6	135.350	C4	C3	H7	134.650

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3LYP/CEP-121G

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	-0.189
2	C	-0.189
3	C	-0.189
4	C	-0.189
5	H	0.189
6	H	0.189
7	H	0.189
8	H	0.189

<r²>	50.537
(<r²>)^1/2	7.109

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3LYP/CEP-121G

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)