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	hartrees
Energy at 0K	-154.631621
Energy at 298.15K	-154.634694
HF Energy	-154.631621
Nuclear repulsion energy	99.288435

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3269	3134	0.00
2	A_g	1662	1594	0.00
3	A_g	1133	1086	0.00
4	A_g	975	935	0.00
5	A_u	882	845	0.00
6	A_u	538	516	0.00
7	B_1g	874	838	0.00
8	B_1u	3257	3122	30.96
9	B_1u	1669	1600	3.22
10	B_1u	1061	1017	0.64
11	B_2g	594	569	0.00
12	B_2u	3235	3101	20.47
13	B_2u	1273	1220	39.12
14	B_2u	740	709	9.52
15	B_3g	3218	3085	0.00
16	B_3g	1187	1138	0.00
17	B_3g	844	809	0.00
18	B_3u	590	565	144.69

Atom	y (Å)	z (Å)
C1	0.663	0.783
C2	0.663	-0.783
C3	-0.663	0.783
C4	-0.663	-0.783
H5	1.429	1.545
H6	1.429	-1.545
H7	-1.429	1.545
H8	-1.429	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5650	1.3269	2.0518	1.0806	2.4503	2.2271	3.1299
C2	1.5650		2.0518	1.3269	2.4503	1.0806	3.1299	2.2271
C3	1.3269	2.0518		1.5650	2.2271	3.1299	1.0806	2.4503
C4	2.0518	1.3269	1.5650		3.1299	2.2271	2.4503	1.0806
H5	1.0806	2.4503	2.2271	3.1299		3.0903	2.8581	4.2094
H6	2.4503	1.0806	3.1299	2.2271	3.0903		4.2094	2.8581
H7	2.2271	3.1299	1.0806	2.4503	2.8581	4.2094		3.0903
H8	3.1299	2.2271	2.4503	1.0806	4.2094	2.8581	3.0903

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.889
C1	C3	C4	90.000	C1	C3	H7	135.111
C2	C1	C3	90.000	C2	C1	H5	134.889
C2	C4	C3	90.000	C3	C1	H5	135.111
C4	C2	H6	135.111	C4	C3	H7	134.889

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B1B95/6-311G*

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	-0.202
2	C	-0.202
3	C	-0.202
4	C	-0.202
5	H	0.202
6	H	0.202
7	H	0.202
8	H	0.202

<r²>	57.338
(<r²>)^1/2	7.572

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B1B95/6-311G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)