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	hartrees
Energy at 0K	-154.273153
Energy at 298.15K
HF Energy	-153.689362
Nuclear repulsion energy	98.743374

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3294	3147	0.00
2	A_g	1592	1520	0.00
3	A_g	1135	1084	0.00
4	A_g	967	923	0.00
5	A_u	614	586	0.00
6	A_u	343i	327i	0.00
7	B_1g	775	741	0.00
8	B_1u	3282	3136	18.69
9	B_1u	1614	1542	5.88
10	B_1u	1068	1021	0.27
11	B_2g	461	440	0.00
12	B_2u	3263	3117	10.29
13	B_2u	1291	1233	31.70
14	B_2u	743	710	7.92
15	B_3g	3248	3103	0.00
16	B_3g	1204	1150	0.00
17	B_3g	869	831	0.00
18	B_3u	574	548	140.05

Atom	y (Å)	z (Å)
C1	0.670	0.785
C2	0.670	-0.785
C3	-0.670	0.785
C4	-0.670	-0.785
H5	1.438	1.544
H6	1.438	-1.544
H7	-1.438	1.544
H8	-1.438	-1.544

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5708	1.3406	2.0651	1.0793	2.4528	2.2406	3.1419
C2	1.5708		2.0651	1.3406	2.4528	1.0793	3.1419	2.2406
C3	1.3406	2.0651		1.5708	2.2406	3.1419	1.0793	2.4528
C4	2.0651	1.3406	1.5708		3.1419	2.2406	2.4528	1.0793
H5	1.0793	2.4528	2.2406	3.1419		3.0885	2.8757	4.2200
H6	2.4528	1.0793	3.1419	2.2406	3.0885		4.2200	2.8757
H7	2.2406	3.1419	1.0793	2.4528	2.8757	4.2200		3.0885
H8	3.1419	2.2406	2.4528	1.0793	4.2200	2.8757	3.0885

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.675
C1	C3	C4	90.000	C1	C3	H7	135.325
C2	C1	C3	90.000	C2	C1	H5	134.675
C2	C4	C3	90.000	C3	C1	H5	135.325
C4	C2	H6	135.325	C4	C3	H7	134.675

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: QCISD/TZVP

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/TZVP

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)