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	hartrees
Energy at 0K	-154.503083
Energy at 298.15K	-154.506164
HF Energy	-154.503083
Nuclear repulsion energy	99.011072

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3288	3138	0.00
2	A_g	1668	1592	0.00
3	A_g	1134	1082	0.00
4	A_g	981	936	0.00
5	A_u	885	844	0.00
6	A_u	541	516	0.00
7	B_1g	868	829	0.00
8	B_1u	3277	3127	23.42
9	B_1u	1680	1603	2.32
10	B_1u	1071	1022	0.36
11	B_2g	600	572	0.00
12	B_2u	3255	3106	10.82
13	B_2u	1277	1219	36.52
14	B_2u	744	710	7.88
15	B_3g	3238	3090	0.00
16	B_3g	1192	1137	0.00
17	B_3g	839	801	0.00
18	B_3u	597	569	122.63

Atom	y (Å)	z (Å)
C1	0.666	0.784
C2	0.666	-0.784
C3	-0.666	0.784
C4	-0.666	-0.784
H5	1.437	1.545
H6	1.437	-1.545
H7	-1.437	1.545
H8	-1.437	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5680	1.3321	2.0575	1.0831	2.4533	2.2361	3.1378
C2	1.5680		2.0575	1.3321	2.4533	1.0831	3.1378	2.2361
C3	1.3321	2.0575		1.5680	2.2361	3.1378	1.0831	2.4533
C4	2.0575	1.3321	1.5680		3.1378	2.2361	2.4533	1.0831
H5	1.0831	2.4533	2.2361	3.1378		3.0904	2.8730	4.2196
H6	2.4533	1.0831	3.1378	2.2361	3.0904		4.2196	2.8730
H7	2.2361	3.1378	1.0831	2.4533	2.8730	4.2196		3.0904
H8	3.1378	2.2361	2.4533	1.0831	4.2196	2.8730	3.0904

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.654
C1	C3	C4	90.000	C1	C3	H7	135.346
C2	C1	C3	90.000	C2	C1	H5	134.654
C2	C4	C3	90.000	C3	C1	H5	135.346
C4	C2	H6	135.346	C4	C3	H7	134.654

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: HSEh1PBE/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	-0.126
2	C	-0.126
3	C	-0.126
4	C	-0.126
5	H	0.126
6	H	0.126
7	H	0.126
8	H	0.126

<r²>	57.334
(<r²>)^1/2	7.572

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: HSEh1PBE/6-31G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)