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	hartrees
Energy at 0K	-154.215432
Energy at 298.15K	-154.218407
HF Energy	-153.647028
Nuclear repulsion energy	98.649055

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3329	3134	0.00
2	A_g	1610	1516	0.00
3	A_g	1155	1087	0.00
4	A_g	981	923	0.00
5	A_u	758	713	0.00
6	A_u	498	469	0.00
7	B_1g	815	767	0.00
8	B_1u	3316	3122	24.57
9	B_1u	1641	1545	2.96
10	B_1u	1084	1021	0.02
11	B_2g	546	514	0.00
12	B_2u	3297	3104	13.06
13	B_2u	1313	1236	27.00
14	B_2u	759	715	7.02
15	B_3g	3283	3090	0.00
16	B_3g	1214	1143	0.00
17	B_3g	872	821	0.00
18	B_3u	586	552	112.45

Atom	y (Å)	z (Å)
C1	0.673	0.785
C2	0.673	-0.785
C3	-0.673	0.785
C4	-0.673	-0.785
H5	1.440	1.543
H6	1.440	-1.543
H7	-1.440	1.543
H8	-1.440	-1.543

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5692	1.3452	2.0669	1.0790	2.4510	2.2446	3.1435
C2	1.5692		2.0669	1.3452	2.4510	1.0790	3.1435	2.2446
C3	1.3452	2.0669		1.5692	2.2446	3.1435	1.0790	2.4510
C4	2.0669	1.3452	1.5692		3.1435	2.2446	2.4510	1.0790
H5	1.0790	2.4510	2.2446	3.1435		3.0864	2.8798	4.2213
H6	2.4510	1.0790	3.1435	2.2446	3.0864		4.2213	2.8798
H7	2.2446	3.1435	1.0790	2.4510	2.8798	4.2213		3.0864
H8	3.1435	2.2446	2.4510	1.0790	4.2213	2.8798	3.0864

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.672
C1	C3	C4	90.000	C1	C3	H7	135.328
C2	C1	C3	90.000	C2	C1	H5	134.672
C2	C4	C3	90.000	C3	C1	H5	135.328
C4	C2	H6	135.328	C4	C3	H7	134.672

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: QCISD/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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All results from a given calculation for C4H4 (cyclobutadiene)

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

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)