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	hartrees
Energy at 0K	-154.468834
Energy at 298.15K	-154.471727
HF Energy	-154.468834
Nuclear repulsion energy	98.169311

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3191	3138	0.00
2	A_g	1603	1577	0.00
3	A_g	1091	1073	0.00
4	A_g	945	929	0.00
5	A_u	824	811	0.00
6	A_u	517	508	0.00
7	B_1g	793	780	0.00
8	B_1u	3180	3127	34.32
9	B_1u	1611	1584	2.32
10	B_1u	1035	1018	0.24
11	B_2g	552	543	0.00
12	B_2u	3159	3107	19.22
13	B_2u	1228	1207	34.87
14	B_2u	696	685	6.16
15	B_3g	3142	3090	0.00
16	B_3g	1139	1120	0.00
17	B_3g	807	794	0.00
18	B_3u	559	550	111.98

Atom	y (Å)	z (Å)
C1	0.672	0.791
C2	0.672	-0.791
C3	-0.672	0.791
C4	-0.672	-0.791
H5	1.450	1.558
H6	1.450	-1.558
H7	-1.450	1.558
H8	-1.450	-1.558

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5814	1.3436	2.0751	1.0924	2.4737	2.2559	3.1647
C2	1.5814		2.0751	1.3436	2.4737	1.0924	3.1647	2.2559
C3	1.3436	2.0751		1.5814	2.2559	3.1647	1.0924	2.4737
C4	2.0751	1.3436	1.5814		3.1647	2.2559	2.4737	1.0924
H5	1.0924	2.4737	2.2559	3.1647		3.1150	2.8996	4.2557
H6	2.4737	1.0924	3.1647	2.2559	3.1150		4.2557	2.8996
H7	2.2559	3.1647	1.0924	2.4737	2.8996	4.2557		3.1150
H8	3.1647	2.2559	2.4737	1.0924	4.2557	2.8996	3.1150

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.586
C1	C3	C4	90.000	C1	C3	H7	135.414
C2	C1	C3	90.000	C2	C1	H5	134.586
C2	C4	C3	90.000	C3	C1	H5	135.414
C4	C2	H6	135.414	C4	C3	H7	134.586

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBEPBEultrafine/6-31G*

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	-0.141
2	C	-0.141
3	C	-0.141
4	C	-0.141
5	H	0.141
6	H	0.141
7	H	0.141
8	H	0.141

<r²>	58.115
(<r²>)^1/2	7.623

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBEPBEultrafine/6-31G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)