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	hartrees
Energy at 0K	-153.169021
Energy at 298.15K	-153.171934
HF Energy	-152.766693
Nuclear repulsion energy	96.728470

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3250	3124	0.00
2	A_g	1506	1447	0.00
3	A_g	1110	1066	0.00
4	A_g	878	844	0.00
5	A_u	752	723	0.00
6	A_u	504	484	0.00
7	B_1g	822	790	0.00
8	B_1u	3233	3107	18.30
9	B_1u	1519	1460	2.42
10	B_1u	1058	1016	0.19
11	B_2g	581	559	0.00
12	B_2u	3213	3088	9.03
13	B_2u	1269	1220	29.62
14	B_2u	616	592	4.58
15	B_3g	3200	3076	0.00
16	B_3g	1199	1152	0.00
17	B_3g	905	870	0.00
18	B_3u	608	585	148.44

Atom	y (Å)	z (Å)
C1	0.681	0.812
C2	0.681	-0.812
C3	-0.681	0.812
C4	-0.681	-0.812
H5	1.452	1.573
H6	1.452	-1.573
H7	-1.452	1.573
H8	-1.452	-1.573

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6244	1.3616	2.1195	1.0835	2.5068	2.2646	3.1998
C2	1.6244		2.1195	1.3616	2.5068	1.0835	3.1998	2.2646
C3	1.3616	2.1195		1.6244	2.2646	3.1998	1.0835	2.5068
C4	2.1195	1.3616	1.6244		3.1998	2.2646	2.5068	1.0835
H5	1.0835	2.5068	2.2646	3.1998		3.1460	2.9044	4.2817
H6	2.5068	1.0835	3.1998	2.2646	3.1460		4.2817	2.9044
H7	2.2646	3.1998	1.0835	2.5068	2.9044	4.2817		3.1460
H8	3.1998	2.2646	2.5068	1.0835	4.2817	2.9044	3.1460

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.604
C1	C3	C4	90.000	C1	C3	H7	135.396
C2	C1	C3	90.000	C2	C1	H5	134.604
C2	C4	C3	90.000	C3	C1	H5	135.396
C4	C2	H6	135.396	C4	C3	H7	134.604

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: QCISD/3-21G*

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/3-21G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)