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	hartrees
Energy at 0K	-154.208606
Energy at 298.15K	-154.211482
HF Energy	-153.654280
Nuclear repulsion energy	98.730750

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3336	3133	0.00
2	A_g	1591	1495	0.00
3	A_g	1149	1079	0.00
4	A_g	989	928	0.00
5	A_u	716	673	0.00
6	A_u	454	426	0.00
7	B_1g	823	773	0.00
8	B_1u	3325	3123	17.38
9	B_1u	1608	1510	5.96
10	B_1u	1080	1014	1.10
11	B_2g	503	472	0.00
12	B_2u	3305	3104	8.96
13	B_2u	1299	1220	33.13
14	B_2u	748	702	6.57
15	B_3g	3291	3091	0.00
16	B_3g	1219	1145	0.00
17	B_3g	860	808	0.00
18	B_3u	567	532	174.65

Atom	y (Å)	z (Å)
C1	0.674	0.782
C2	0.674	-0.782
C3	-0.674	0.782
C4	-0.674	-0.782
H5	1.438	1.543
H6	1.438	-1.543
H7	-1.438	1.543
H8	-1.438	-1.543

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5640	1.3470	2.0642	1.0787	2.4476	2.2443	3.1408
C2	1.5640		2.0642	1.3470	2.4476	1.0787	3.1408	2.2443
C3	1.3470	2.0642		1.5640	2.2443	3.1408	1.0787	2.4476
C4	2.0642	1.3470	1.5640		3.1408	2.2443	2.4476	1.0787
H5	1.0787	2.4476	2.2443	3.1408		3.0864	2.8756	4.2184
H6	2.4476	1.0787	3.1408	2.2443	3.0864		4.2184	2.8756
H7	2.2443	3.1408	1.0787	2.4476	2.8756	4.2184		3.0864
H8	3.1408	2.2443	2.4476	1.0787	4.2184	2.8756	3.0864

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.884
C1	C3	C4	90.000	C1	C3	H7	135.116
C2	C1	C3	90.000	C2	C1	H5	134.884
C2	C4	C3	90.000	C3	C1	H5	135.116
C4	C2	H6	135.116	C4	C3	H7	134.884

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: MP2=FULL/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: MP2=FULL/6-31+G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)