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	hartrees
Energy at 0K	-154.615789
Energy at 298.15K	-154.618825
HF Energy	-154.615789
Nuclear repulsion energy	98.836625

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3275	3133	0.00
2	A_g	1656	1584	0.00
3	A_g	1129	1080	0.00
4	A_g	973	931	0.00
5	A_u	873	835	0.00
6	A_u	539	516	0.00
7	B_1g	850	813	0.00
8	B_1u	3264	3123	28.77
9	B_1u	1667	1595	2.53
10	B_1u	1069	1023	0.30
11	B_2g	588	563	0.00
12	B_2u	3243	3102	15.95
13	B_2u	1274	1219	36.04
14	B_2u	732	700	7.70
15	B_3g	3226	3086	0.00
16	B_3g	1186	1134	0.00
17	B_3g	838	802	0.00
18	B_3u	589	563	126.15

Atom	y (Å)	z (Å)
C1	0.667	0.786
C2	0.667	-0.786
C3	-0.667	0.786
C4	-0.667	-0.786
H5	1.439	1.548
H6	1.439	-1.548
H7	-1.439	1.548
H8	-1.439	-1.548

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5720	1.3338	2.0616	1.0843	2.4578	2.2392	3.1431
C2	1.5720		2.0616	1.3338	2.4578	1.0843	3.1431	2.2392
C3	1.3338	2.0616		1.5720	2.2392	3.1431	1.0843	2.4578
C4	2.0616	1.3338	1.5720		3.1431	2.2392	2.4578	1.0843
H5	1.0843	2.4578	2.2392	3.1431		3.0950	2.8776	4.2261
H6	2.4578	1.0843	3.1431	2.2392	3.0950		4.2261	2.8776
H7	2.2392	3.1431	1.0843	2.4578	2.8776	4.2261		3.0950
H8	3.1431	2.2392	2.4578	1.0843	4.2261	2.8776	3.0950

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.613
C1	C3	C4	90.000	C1	C3	H7	135.387
C2	C1	C3	90.000	C2	C1	H5	134.613
C2	C4	C3	90.000	C3	C1	H5	135.387
C4	C2	H6	135.387	C4	C3	H7	134.613

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3PW91/6-31G*

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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Calc. vs exp. Bad Vib. HF vs MP2 Bad scale factors Low excited states Oddities NaCN Is not linear FAQ Help Units Choose Units Energy Bond length Rotational Constant Moment of Inertia Dipole and Quadrupole Polarizability Explanations Hartree cm-1 Debye Credits Just show me Show me a calculated geometry Summary Using older interface Limit Basis sets Method options List Recent molecules Choose a few Molecules Number of atoms By heavy atoms Diatomics InChI Deuterated Dimers Geometry Point group Point group count Bonds types Isodesmic reactions Bad point group Multiple conformers, states Vibrations Big anharmonicity Energy Enthalpy at 0 Kelvin Similar molecules Similar Isomers Cis/trans Tautomers Multiple conformers, states Ions, Dipoles, etc. List Ions Ionization changes point group Dipole Quadrupole Polarizability Proton Affinities Index of CCCBDB Feedback Error form Wants
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Number	Element	Mulliken
1	C	-0.165
2	C	-0.165
3	C	-0.165
4	C	-0.165
5	H	0.165
6	H	0.165
7	H	0.165
8	H	0.165

<r²>	57.457
(<r²>)^1/2	7.580

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3PW91/6-31G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)