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	hartrees
Energy at 0K	-154.224136
Energy at 298.15K	-154.227071
HF Energy	-153.654078
Nuclear repulsion energy	98.555536

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3324	3142	0.00
2	A_g	1597	1510	0.00
3	A_g	1150	1087	0.00
4	A_g	976	923	0.00
5	A_u	728	688	0.00
6	A_u	480	454	0.00
7	B_1g	819	774	0.00
8	B_1u	3312	3131	20.32
9	B_1u	1626	1537	7.35
10	B_1u	1078	1019	0.38
11	B_2g	528	499	0.00
12	B_2u	3293	3113	12.11
13	B_2u	1308	1237	31.13
14	B_2u	755	714	7.88
15	B_3g	3279	3100	0.00
16	B_3g	1214	1148	0.00
17	B_3g	872	824	0.00
18	B_3u	581	550	161.00

Atom	y (Å)	z (Å)
C1	0.674	0.785
C2	0.674	-0.785
C3	-0.674	0.785
C4	-0.674	-0.785
H5	1.440	1.545
H6	1.440	-1.545
H7	-1.440	1.545
H8	-1.440	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5693	1.3480	2.0687	1.0794	2.4524	2.2468	3.1460
C2	1.5693		2.0687	1.3480	2.4524	1.0794	3.1460	2.2468
C3	1.3480	2.0687		1.5693	2.2468	3.1460	1.0794	2.4524
C4	2.0687	1.3480	1.5693		3.1460	2.2468	2.4524	1.0794
H5	1.0794	2.4524	2.2468	3.1460		3.0901	2.8803	4.2243
H6	2.4524	1.0794	3.1460	2.2468	3.0901		4.2243	2.8803
H7	2.2468	3.1460	1.0794	2.4524	2.8803	4.2243		3.0901
H8	3.1460	2.2468	2.4524	1.0794	4.2243	2.8803	3.0901

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.784
C1	C3	C4	90.000	C1	C3	H7	135.216
C2	C1	C3	90.000	C2	C1	H5	134.784
C2	C4	C3	90.000	C3	C1	H5	135.216
C4	C2	H6	135.216	C4	C3	H7	134.784

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: QCISD/6-31+G**

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: QCISD/6-31+G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)