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	hartrees
Energy at 0K	-153.818322
Energy at 298.15K	-153.821434
HF Energy	-153.818322
Nuclear repulsion energy	97.742660

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3293	3177	0.00
2	A_g	1613	1557	0.00
3	A_g	1109	1070	0.00
4	A_g	921	889	0.00
5	A_u	924	891	0.00
6	A_u	555	536	0.00
7	B_1g	914	882	0.00
8	B_1u	3277	3162	17.84
9	B_1u	1603	1547	2.59
10	B_1u	1072	1035	0.32
11	B_2g	648	625	0.00
12	B_2u	3254	3140	6.35
13	B_2u	1264	1220	39.10
14	B_2u	629	607	5.72
15	B_3g	3239	3125	0.00
16	B_3g	1206	1163	0.00
17	B_3g	895	864	0.00
18	B_3u	633	611	171.39

Atom	y (Å)	z (Å)
C1	0.670	0.806
C2	0.670	-0.806
C3	-0.670	0.806
C4	-0.670	-0.806
H5	1.439	1.562
H6	1.439	-1.562
H7	-1.439	1.562
H8	-1.439	-1.562

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6124	1.3402	2.0966	1.0782	2.4899	2.2403	3.1712
C2	1.6124		2.0966	1.3402	2.4899	1.0782	3.1712	2.2403
C3	1.3402	2.0966		1.6124	2.2403	3.1712	1.0782	2.4899
C4	2.0966	1.3402	1.6124		3.1712	2.2403	2.4899	1.0782
H5	1.0782	2.4899	2.2403	3.1712		3.1241	2.8778	4.2476
H6	2.4899	1.0782	3.1712	2.2403	3.1241		4.2476	2.8778
H7	2.2403	3.1712	1.0782	2.4899	2.8778	4.2476		3.1241
H8	3.1712	2.2403	2.4899	1.0782	4.2476	2.8778	3.1241

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.512
C1	C3	C4	90.000	C1	C3	H7	135.488
C2	C1	C3	90.000	C2	C1	H5	134.512
C2	C4	C3	90.000	C3	C1	H5	135.488
C4	C2	H6	135.488	C4	C3	H7	134.512

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3LYP/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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Number	Element	Mulliken
1	C	-0.180
2	C	-0.180
3	C	-0.180
4	C	-0.180
5	H	0.180
6	H	0.180
7	H	0.180
8	H	0.180

<r²>	58.774
(<r²>)^1/2	7.666

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3LYP/3-21G

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)