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	hartrees
Energy at 0K	-153.741515
Energy at 298.15K	-153.744645
HF Energy	-153.741515
Nuclear repulsion energy	97.949712

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3254	3120	0.00
2	A_g	1629	1561	0.00
3	A_g	1109	1063	0.00
4	A_g	938	899	0.00
5	A_u	938	899	0.00
6	A_u	549	526	0.00
7	B_1g	932	894	0.00
8	B_1u	3239	3105	6.34
9	B_1u	1620	1553	2.03
10	B_1u	1062	1018	0.57
11	B_2g	652	625	0.00
12	B_2u	3216	3083	0.39
13	B_2u	1258	1206	40.06
14	B_2u	662	635	5.52
15	B_3g	3201	3069	0.00
16	B_3g	1194	1145	0.00
17	B_3g	896	859	0.00
18	B_3u	623	597	187.32

Atom	y (Å)	z (Å)
C1	0.669	0.803
C2	0.669	-0.803
C3	-0.669	0.803
C4	-0.669	-0.803
H5	1.437	1.558
H6	1.437	-1.558
H7	-1.437	1.558
H8	-1.437	-1.558

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6070	1.3384	2.0913	1.0769	2.4834	2.2377	3.1646
C2	1.6070		2.0913	1.3384	2.4834	1.0769	3.1646	2.2377
C3	1.3384	2.0913		1.6070	2.2377	3.1646	1.0769	2.4834
C4	2.0913	1.3384	1.6070		3.1646	2.2377	2.4834	1.0769
H5	1.0769	2.4834	2.2377	3.1646		3.1163	2.8748	4.2398
H6	2.4834	1.0769	3.1646	2.2377	3.1163		4.2398	2.8748
H7	2.2377	3.1646	1.0769	2.4834	2.8748	4.2398		3.1163
H8	3.1646	2.2377	2.4834	1.0769	4.2398	2.8748	3.1163

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.491
C1	C3	C4	90.000	C1	C3	H7	135.509
C2	C1	C3	90.000	C2	C1	H5	134.491
C2	C4	C3	90.000	C3	C1	H5	135.509
C4	C2	H6	135.509	C4	C3	H7	134.491

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: M06-2X/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	-0.205
2	C	-0.205
3	C	-0.205
4	C	-0.205
5	H	0.205
6	H	0.205
7	H	0.205
8	H	0.205

<r²>	58.638
(<r²>)^1/2	7.658

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: M06-2X/3-21G

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)