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	hartrees
Energy at 0K	-154.171517
Energy at 298.15K	-154.174436
HF Energy	-153.639654
Nuclear repulsion energy	98.719348

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3316	3112	0.00
2	A_g	1660	1558	0.00
3	A_g	1156	1085	0.00
4	A_g	990	929	0.00
5	A_u	729	684	0.00
6	A_u	494	464	0.00
7	B_1g	802	752	0.00
8	B_1u	3305	3102	20.56
9	B_1u	1675	1572	1.75
10	B_1u	1086	1019	0.33
11	B_2g	518	486	0.00
12	B_2u	3285	3084	10.27
13	B_2u	1305	1225	32.53
14	B_2u	755	709	7.37
15	B_3g	3272	3071	0.00
16	B_3g	1208	1134	0.00
17	B_3g	883	828	0.00
18	B_3u	574	538	132.69

Atom	y (Å)	z (Å)
C1	0.669	0.786
C2	0.669	-0.786
C3	-0.669	0.786
C4	-0.669	-0.786
H5	1.441	1.546
H6	1.441	-1.546
H7	-1.441	1.546
H8	-1.441	-1.546

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5718	1.3386	2.0646	1.0828	2.4560	2.2426	3.1447
C2	1.5718		2.0646	1.3386	2.4560	1.0828	3.1447	2.2426
C3	1.3386	2.0646		1.5718	2.2426	3.1447	1.0828	2.4560
C4	2.0646	1.3386	1.5718		3.1447	2.2426	2.4560	1.0828
H5	1.0828	2.4560	2.2426	3.1447		3.0919	2.8811	4.2261
H6	2.4560	1.0828	3.1447	2.2426	3.0919		4.2261	2.8811
H7	2.2426	3.1447	1.0828	2.4560	2.8811	4.2261		3.0919
H8	3.1447	2.2426	2.4560	1.0828	4.2261	2.8811	3.0919

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.582
C1	C3	C4	90.000	C1	C3	H7	135.418
C2	C1	C3	90.000	C2	C1	H5	134.582
C2	C4	C3	90.000	C3	C1	H5	135.418
C4	C2	H6	135.418	C4	C3	H7	134.582

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: MP3/6-31G*

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: MP3/6-31G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)