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	hartrees
Energy at 0K	-153.624952
Energy at 298.15K	-153.628105
HF Energy	-153.624952
Nuclear repulsion energy	97.942423

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3319	3188	0.00
2	A_g	1630	1565	0.00
3	A_g	1117	1072	0.00
4	A_g	943	906	0.00
5	A_u	933	896	0.00
6	A_u	554	532	0.00
7	B_1g	929	892	0.00
8	B_1u	3302	3172	12.74
9	B_1u	1620	1556	1.54
10	B_1u	1074	1031	1.17
11	B_2g	661	635	0.00
12	B_2u	3279	3149	3.48
13	B_2u	1267	1216	42.35
14	B_2u	658	632	6.01
15	B_3g	3263	3134	0.00
16	B_3g	1207	1160	0.00
17	B_3g	895	860	0.00
18	B_3u	648	622	194.22

Atom	y (Å)	z (Å)
C1	0.670	0.802
C2	0.670	-0.802
C3	-0.670	0.802
C4	-0.670	-0.802
H5	1.439	1.559
H6	1.439	-1.559
H7	-1.439	1.559
H8	-1.439	-1.559

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6043	1.3398	2.0902	1.0786	2.4830	2.2401	3.1655
C2	1.6043		2.0902	1.3398	2.4830	1.0786	3.1655	2.2401
C3	1.3398	2.0902		1.6043	2.2401	3.1655	1.0786	2.4830
C4	2.0902	1.3398	1.6043		3.1655	2.2401	2.4830	1.0786
H5	1.0786	2.4830	2.2401	3.1655		3.1179	2.8770	4.2424
H6	2.4830	1.0786	3.1655	2.2401	3.1179		4.2424	2.8770
H7	2.2401	3.1655	1.0786	2.4830	2.8770	4.2424		3.1179
H8	3.1655	2.2401	2.4830	1.0786	4.2424	2.8770	3.1179

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.556
C1	C3	C4	90.000	C1	C3	H7	135.444
C2	C1	C3	90.000	C2	C1	H5	134.556
C2	C4	C3	90.000	C3	C1	H5	135.444
C4	C2	H6	135.444	C4	C3	H7	134.556

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBE1PBE/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	-0.215
2	C	-0.215
3	C	-0.215
4	C	-0.215
5	H	0.215
6	H	0.215
7	H	0.215
8	H	0.215

<r²>	58.541
(<r²>)^1/2	7.651

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBE1PBE/3-21G

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)