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	hartrees
Energy at 0K	-24.637579
Energy at 298.15K	-24.640093
HF Energy	-24.127402
Nuclear repulsion energy	49.932899

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3267	3112	0.00
2	A_g	1548	1475	0.00
3	A_g	1130	1076	0.00
4	A_g	979	932	0.00
5	A_u	609	580	0.00
6	A_u	261	249	0.00
7	B_1g	746	710	0.00
8	B_1u	3257	3103	25.35
9	B_1u	1561	1487	3.61
10	B_1u	1057	1007	1.51
11	B_2g	447	426	0.00
12	B_2u	3237	3084	14.17
13	B_2u	1267	1207	34.01
14	B_2u	745	710	7.27
15	B_3g	3224	3071	0.00
16	B_3g	1165	1110	0.00
17	B_3g	852	812	0.00
18	B_3u	559	532	177.60

Atom	y (Å)	z (Å)
C1	0.678	0.790
C2	0.678	-0.790
C3	-0.678	0.790
C4	-0.678	-0.790
H5	1.449	1.555
H6	1.449	-1.555
H7	-1.449	1.555
H8	-1.449	-1.555

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5796	1.3568	2.0823	1.0861	2.4681	2.2610	3.1661
C2	1.5796		2.0823	1.3568	2.4681	1.0861	3.1661	2.2610
C3	1.3568	2.0823		1.5796	2.2610	3.1661	1.0861	2.4681
C4	2.0823	1.3568	1.5796		3.1661	2.2610	2.4681	1.0861
H5	1.0861	2.4681	2.2610	3.1661		3.1098	2.8985	4.2511
H6	2.4681	1.0861	3.1661	2.2610	3.1098		4.2511	2.8985
H7	2.2610	3.1661	1.0861	2.4681	2.8985	4.2511		3.1098
H8	3.1661	2.2610	2.4681	1.0861	4.2511	2.8985	3.1098

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.787
C1	C3	C4	90.000	C1	C3	H7	135.213
C2	C1	C3	90.000	C2	C1	H5	134.787
C2	C4	C3	90.000	C3	C1	H5	135.213
C4	C2	H6	135.213	C4	C3	H7	134.787

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: MP2/CEP-121G*

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/CEP-121G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)