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	hartrees
Energy at 0K	-154.606703
Energy at 298.15K	-154.609767
HF Energy	-154.606703
Nuclear repulsion energy	99.062151

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3268	3106	0.00
2	A_g	1676	1593	0.00
3	A_g	1134	1078	0.00
4	A_g	977	928	0.00
5	A_u	893	849	0.00
6	A_u	537	511	0.00
7	B_1g	879	835	0.00
8	B_1u	3258	3096	17.06
9	B_1u	1688	1604	2.69
10	B_1u	1066	1013	0.16
11	B_2g	590	561	0.00
12	B_2u	3235	3075	4.59
13	B_2u	1275	1212	36.06
14	B_2u	748	711	6.85
15	B_3g	3219	3059	0.00
16	B_3g	1186	1128	0.00
17	B_3g	835	793	0.00
18	B_3u	578	549	123.19

Atom	y (Å)	z (Å)
C1	0.665	0.784
C2	0.665	-0.784
C3	-0.665	0.784
C4	-0.665	-0.784
H5	1.435	1.545
H6	1.435	-1.545
H7	-1.435	1.545
H8	-1.435	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5690	1.3301	2.0569	1.0822	2.4536	2.2334	3.1364
C2	1.5690		2.0569	1.3301	2.4536	1.0822	3.1364	2.2334
C3	1.3301	2.0569		1.5690	2.2334	3.1364	1.0822	2.4536
C4	2.0569	1.3301	1.5690		3.1364	2.2334	2.4536	1.0822
H5	1.0822	2.4536	2.2334	3.1364		3.0906	2.8694	4.2173
H6	2.4536	1.0822	3.1364	2.2334	3.0906		4.2173	2.8694
H7	2.2334	3.1364	1.0822	2.4536	2.8694	4.2173		3.0906
H8	3.1364	2.2334	2.4536	1.0822	4.2173	2.8694	3.0906

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.669
C1	C3	C4	90.000	C1	C3	H7	135.331
C2	C1	C3	90.000	C2	C1	H5	134.669
C2	C4	C3	90.000	C3	C1	H5	135.331
C4	C2	H6	135.331	C4	C3	H7	134.669

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: M06-2X/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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Number	Element	Mulliken
1	C	-0.126
2	C	-0.126
3	C	-0.126
4	C	-0.126
5	H	0.126
6	H	0.126
7	H	0.126
8	H	0.126

<r²>	57.375
(<r²>)^1/2	7.575

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: M06-2X/6-31G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)