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	hartrees
Energy at 0K	-154.151376
Energy at 298.15K	-154.154510
HF Energy	-153.669756
Nuclear repulsion energy	99.091836

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3344	3094	0.00
2	A_g	1685	1559	0.00
3	A_g	1169	1082	0.00
4	A_g	1001	926	0.00
5	A_u	844	781	0.00
6	A_u	542	502	0.00
7	B_1g	887	820	0.00
8	B_1u	3331	3082	21.43
9	B_1u	1696	1569	3.37
10	B_1u	1094	1012	0.57
11	B_2g	600	555	0.00
12	B_2u	3309	3062	12.47
13	B_2u	1322	1223	37.54
14	B_2u	777	719	10.77
15	B_3g	3294	3048	0.00
16	B_3g	1222	1130	0.00
17	B_3g	887	821	0.00
18	B_3u	615	569	159.02

Atom	y (Å)	z (Å)
C1	0.665	0.785
C2	0.665	-0.785
C3	-0.665	0.785
C4	-0.665	-0.785
H5	1.430	1.545
H6	1.430	-1.545
H7	-1.430	1.545
H8	-1.430	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5696	1.3309	2.0578	1.0782	2.4517	2.2293	3.1334
C2	1.5696		2.0578	1.3309	2.4517	1.0782	3.1334	2.2293
C3	1.3309	2.0578		1.5696	2.2293	3.1334	1.0782	2.4517
C4	2.0578	1.3309	1.5696		3.1334	2.2293	2.4517	1.0782
H5	1.0782	2.4517	2.2293	3.1334		3.0891	2.8608	4.2103
H6	2.4517	1.0782	3.1334	2.2293	3.0891		4.2103	2.8608
H7	2.2293	3.1334	1.0782	2.4517	2.8608	4.2103		3.0891
H8	3.1334	2.2293	2.4517	1.0782	4.2103	2.8608	3.0891

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.805
C1	C3	C4	90.000	C1	C3	H7	135.195
C2	C1	C3	90.000	C2	C1	H5	134.805
C2	C4	C3	90.000	C3	C1	H5	135.195
C4	C2	H6	135.195	C4	C3	H7	134.805

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: CISD/6-311G*

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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All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: CISD/6-311G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)